• Title/Summary/Keyword: PTO

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Experimental study of wave energy extraction by a dual-buoy heaving system

  • Kim, J.;Koh, H.J.;Cho, I.H.;Kim, M.H.;Kweon, H.M.
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.9 no.1
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    • pp.25-34
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    • 2017
  • The concentric dual-buoy Wave Energy Converter (WEC), which consists of external buoy (hallow-cylinder) with toroidal appendage and cylindrical internal buoy within the moon-pool is suggested in this research and its performance in various wave conditions is studied. The Linear Electric Generator (LEG), consisting of a permanent magnet and coils, is used as a direct Power Take-Off (PTO) system. To maximize the electrical energy extracted from the PTO system, the relative heave motions between the dual buoys must be highly amplified by the multiple resonance phenomena of dual-buoy and internal-fluid motions. The high-performance range can be widened by distributing those natural frequencies with respect to the peak frequency of the wave spectrum. The performance of the newly developed dual-buoy WEC was measured throughout the systematic 1:5.95-model test in regular and irregular waves conducted in a wave tank at Seoul National University. The model-test results are also validated by an independently developed numerical method.

Motion Analysis of A Wind-Wave Energy TLP Platform Considering Second-order Wave Forces

  • Hongbhin Kim;Eun-hong Min;Sanghwan Heo;WeonCheol Koo
    • Journal of Ocean Engineering and Technology
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    • v.36 no.6
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    • pp.390-402
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    • 2022
  • Offshore wind energy has become a major energy source, and various studies are underway to increase the economic feasibility of floating offshore wind turbines (FOWT). In this study, the characteristics of wave-induced motion of a combined wind-wave energy platform were analyzed to reduce the variability of energy extraction. A user subroutine was developed, and numerical analysis was performed in connection with the ANSYS-AQWA hydrodynamic program in the time domain. A platform combining the TLP-type FOWT and the Wavestar-type wave energy converter (WEC) was proposed. Each motion response of the platform on the second-order wave load, the effect of WEC attachment and Power take-off (PTO) force were analyzed. The mooring line tension according to the installation location was also analyzed. The vertical motion of a single FOWT was increased approximately three times due to the second-order sum-frequency wave load. The PTO force of the WEC played as a vertical motion damper for the combined platform. The tension of the mooring lines in front of the incident wave direction was dominantly affected by the pitch of the platform, and the mooring lines located at the side of the platform were mainly affected by the heave of the platform.

The Influence of Unstable Wall Squat Exercise and Stable Bridge Exercise on Posture in Normal Adults (불안정한 지지면에서의 벽 스쿼트 운동과 안정된 지지면에서의 브릿지 운동이 정상 성인의 자세에 미치는 영향)

  • Gong, Won-tae
    • The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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    • v.28 no.1
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    • pp.1-7
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    • 2022
  • Purpose: The purpose of this study is to examine the unstable wall squat exercise and stable bridge exercise on posture in normal adults. Methods: The subjects of this study were 34 university students who were normal health adults, equally and randomly allocated to a unstable wall squat exercise group (male 7, female 10), an experimental group, and a stable bridge exercise group, a control group. Both did so for 30 minutes three times per week over a six-weeks period. Using Back Mapper, their trunk inclination (TIN), trunk imbalance (TIM), pelvic position (PPO), pelvic torsion (PTO), pelvic rotation (PRO) and the position of their scapula (PSA) were evaluated. Results: When the pre-test and post-test results of experimental group and control group were compared, statistically significant differences in TIN, PTO and PSA of experimental group were seen. Conclusion: Unstable wall squat exercise accompanied by abdominal drawing-in may be applied as a method to correct the posture in normal adults.

MOTORCYCLE POWER TAKE-OFF FOR AGRICULTURE

  • Quick, G.R.;Paita, B.L.;Salazar, G.C.
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • 1993.10a
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    • pp.211-216
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    • 1993
  • The successful design of several types of motorcycle power take off (M-pto) has opened possibilities for the use of a range of attachments matched to the power of the more popular motorcycle models in Asia. This paper reports on the implementation of the motorcycle power-take-off for low-speed and high speed applications utilizing some existing IRRI machines.

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One-way Coupled Response Analysis between Floating Wind-Wave Hybrid Platform and Wave Energy Converters (부유식 풍력-파력발전 플랫폼과 탑재된 파력발전기와의 단방향 연성 운동 해석)

  • Lee, Hyebin;Bae, Yoon Hyeok;Cho, Il-Hyoung
    • Journal of Ocean Engineering and Technology
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    • v.30 no.2
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    • pp.84-90
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    • 2016
  • In this study, a six degree-of-freedom motion analysis of a wind-wave hybrid platform equipped with numerous wave energy converters (WECs) was carried out. To examine the effect of the WECs on the platform, an analysis of one-way coupling was carried out, which only considered the power take-off (PTO) damping of the static WECs on the platform. The equation of motion of a floating platform with mooring lines in the time domain was established, and the responses of the one-way coupled platform were then compared with the case of a platform without any coupling effects from the WECs. The hydrodynamic coefficients and wave exciting forces were obtained from the 3D diffraction/radiation pre-processor code WAMIT based on the boundary element method. Then, an analysis of the dynamic responses of the floating platform with or without the WEC effect in the time domain was carried out. All of the dynamics of a floating platform with multiple wind turbines were obtained by coupling FAST and CHARM3D in the time domain, which was further extended to include additional coupled dynamics for multiple turbines. The analysis showed that the PTO damping effect on platform motions was negligible, but coupled effects between multiple WECs and the platform may differentiate the heave, roll, and pitch platform motions from the one without any effects induced by WECs.

Numerical Study on Shape Optimization of a Heaving Hemisphere Wave Energy Converter (상하 운동 반구형 파력 발전기의 최적 형상 조건 수치해석)

  • Kim, Sung-Jae;Koo, Weoncheol;Heo, Kyung-Uk;Heo, Sanghwan
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.18 no.4
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    • pp.254-262
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    • 2015
  • Parametric study on submerged body shape of an oscillating hemisphere point absorber was conducted to predict the optimal relation between radius and draft of the body. As an additional damping due to power takeoff system, the optimal damping same as wave radiation damping was applied to the PTO system to produce the maximum wave power. Body response spectrum and power spectrum were obtained for various peak frequencies on wave spectra. It was found that the maximum power can be generated when the peak frequency of available wave power was 20% greater than that of wave spectrum.

Pre-processing of load data of agricultural tractors during major field operations

  • Ryu, Myong-Jin;Kabir, Md. Shaha Nur;Choo, Youn-Kug;Chung, Sun-Ok;Kim, Yong-Joo;Ha, Jong-Kyou;Lee, Kyeong-Hwan
    • Korean Journal of Agricultural Science
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    • v.42 no.1
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    • pp.53-61
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    • 2015
  • Development of highly efficient and energy-saving tractors has been one of the issues in agricultural machinery. For design of such tractors, measurement and analysis of load on major power transmission parts of the tractors are the most important pre-requisite tasks. Objective of this study was to perform pre-processing procedures before effective analysis of load data of agricultural tractors (30, 75, and 82 kW) during major field operations such as plow tillage, rotary tillage, baling, bale wrapping, and to select the suitable pre-processing method for the analysis. A load measurement systems, equipped in the tractors, were consisted of strain-gauge, encoder, hydraulic pressure, and radar speed sensors to measure torque and rotational speed levels of transmission input shaft, PTO shaft, and driving axle shafts, pressure of the hydraulic inlet line, and travel speed, respectively. The entire sensor data were collected at a 200-Hz rate. Plow tillage, rotary tillage, baling, wrapping, and loader operations were selected as major field operations of agricultural tractors. Same or different farm works and driving levels were set differently for each of the load measuring experiment. Before load data analysis, pre-processing procedures such as outlier removal, low-pass filtering, and data division were performed. Data beyond the scope of the measuring range of the sensors and the operating range of the power transmission parts were removed. Considering engine and PTO rotational speeds, frequency components greater than 90, 60, and 60 Hz cut off frequencies were low-pass filtered for plow tillage, rotary tillage, and baler operations, respectively. Measured load data were divided into five parts: driving, working, implement up, implement down, and turning. Results of the study would provide useful information for load characteristics of tractors on major field operations.

Comparison of Test Standards for the Performance and Safety of Agricultural Tractors: A Review

  • Kabir, Md. Shaha Nur;Chung, Sun-Ok;Kim, Yong-Joo;Shin, Sung-Hyun
    • Journal of Biosystems Engineering
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    • v.39 no.3
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    • pp.158-165
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    • 2014
  • Purpose: The objective of this paper was to compare test standards regarding the performance and safety of agricultural tractors to identify the differences in test conditions, measurement tolerances, and test procedures. Based on the comparison, some recommendations were proposed for possible revisions or improvements to current tractor test standards. Methods: The test standards and codes of major standards development organizations (SDOs), such as the Organization for Economic Cooperation and Development (OECD), the International Organization for Standardization (ISO), the American Society of Agricultural and Biological Engineers (ASABE), EC type approval, and the board of actions of the Nebraska Tractor Test Laboratories (NTTL), were selected and analyzed. Comparison of the test standards: The ISO provides references for fuel and lubricants for tractor tests, and the OECD provides additional measurements for calculating fuel consumption characteristics during the power take-off (PTO) tests. The ISO, EC type approval, and the ASABE provide PTO protective device and the safety requirements. During drawbar power tests, seven transmission ratios are selected for fully automatic transmissions, according to the OECD. In case of hydraulic lift tests, ISO 789-2 and OECD Code 2 advise the use of a static lift force, while SAE J283 advises the use of additional dynamic lift capacity tests for a better representation of in-field operations. The OECD, the ISO, and EC type approval determine the seat index point (SIP), whereas the ASABE determines the seat reference point (SRP) for roll-over protective structure (ROPS) tests. Diversified measurement tolerances were among the braking performance test standards. The European Union (EU) has developed daily limits for vibration exposures with adaptations from ISO 2631-1. Electromagnetic compatibility evaluations are emerging of high-efficiency tractors due to the long-term conformance to electromagnetic emissions and interferences. Comparisons of tractor test standards discussed in this paper are expected to provide useful information for tractor manufacturers and standards development personnel to improve the performance and safety test standards of tractors.

Wave-Energy Extraction by a Compact Circular Array of Buoys (원형으로 배열된 다수 부이에 의한 파랑에너지 추출)

  • Cho, Il-Hyoung
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.26 no.2
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    • pp.103-111
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    • 2014
  • The wave power, extracted from a circular array of small power buoys, is investigated under the potential theory. It is assumed that the buoy's radius, the draft, and the separation distance are much smaller than the water depth, the wave length, and the radius of a circular deployment area. The boundary value problem involving the macro-scale boundary condition on the mean surface covered by buoys is solved using the eigenfunction expansion method. The capture width, which is defined as the ratio of the extracted power to the wave power per unit length of the incident wave crest, is assessed for various combinations of packing ratio, radius of a circular array, and PTO damping coefficient. It is found that the circular array deployment is more effective in the viewpoint of efficiency than the single large buoy of the same total displaced volume.

Power Conversion System for Electric Power Take-off of Agricultural Electric Vehicle (농업용 전기차량의 전기식 동력인출장치용 전력변환시스템)

  • Kwak, Bongwoo;Kim, Jonghoon
    • Journal of IKEEE
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    • v.23 no.3
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    • pp.994-1002
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    • 2019
  • In this paper, we propose the development of a power conversion system for electric power take-off (e-PTO) of agricultural electric vehicles. Most e-PTOs use commercial power $220V_{AC}$. A bidirectional power conversion system having a two-stage structure consisting of a DC-DC converter and a DC-AC inverter for supplying a high output voltage using a low battery voltage of an agricultural electric vehicle is suitable. we propose a power conversion system consisting of the one-stage dual active bridge (DAB) converter and the two-stage bidirectional full bridge inverter. In addition, we propose a soft start algorithm for reducing the inrush current generated by the link capacitor charging during the initial operation. A 3kW prototype system and its corresponding algorithms have been implemented to verify its effectiveness through experiments.