• Animal cells and systems
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• 제2권4호
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• pp.477-481
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• 1998

Previous studies have postulated that isometric animals exert similar locomotory capacity (speed, distance) because the amount of energy available for the motion would be the same regardless of body mass (m). To test propriety of this theory, we examined body shape and take-off potential of two frog species, Rana nigromaculata (powerful jumpers) and Bombina orientalis (slow hoppers). Morphological measurements included thigh muscle mass (indicative of total muscle force), hindlimb length (L, determining acceleration distance), and interilial width (shaping take-off motion). To gauge locomotory capacity, take-off speed (v) and take-off angle ($\theta$) were measured from video analyses, and jump distance (R) and take-off Power ($P_{t}$ ) were calculated from equations $R=V^{2}sin2\theta/g$ and ($P_{t}$＝$㎷^{3}/2L$(where g is the gravitational constant). Scaling exponents of morphometric variables for both species were 0.96-1.11 for thigh muscle mass, 0.28-0.29 for hindlimb length, and 0.30-0.36 for interilial width. Scaling exponents of locomotory performance for the two species were -0.01-0.14 for take-off speed, 0.24-0.31 for jump distance, and 0.66-0.84 for take-off power. The results demonstrate that the frogs of this study showed isometric body shape within species, but that take-off response changed allometrically with body mass, indicating that these data did not fully support the previous proposition. An exception was found in take-off speed of B. orientalis, in which the speed changed little with body mass (slope＝-0.01). These findings suggest that the energy availability approach did not properly explain the apparent allometric relations of the take-off response in these animals and that an alternative model such as a power production approach may be worth addressing.

• 한국동물학회지
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• 제39권2호
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• pp.132-138
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• 1996

To learn how maximal locomotory speed of animals is defined in terms of hindlimb structure and muscle contractile function, take-off speed, hindlimb length, thigh muscle mass, shortening velocity and power of the sastrocnemius muscle were measured with one fast species, Rono nigromaculota and one relatively slowresponding species, Bombina orientalis. Take-off speed (m.sec-1) was greater in R. nigromoculata $(2.4\pm0.2SD, $ n: 14) than in the Bombino $(1.6\pm0.1SD, $ n=8). Stvle of the take-off response was a long-iump type in the Rano and a short-ranged hopping in the Bombing. Faster take-off capacity of the ranid frogs was supported by the longer hindlimb length (relative to body length) and the more massive thigh muscles (relative to body mass), compared to the Bombina. Further, the ranids exhibited faster maximal shortening velocity and Breater maximal power generateion than the Bombina [Vmax $(ML.sec-1)=11.79\pm1.69SD$ for the Runa and $9.74\pm1.27SD$ for the Bombina; Pmax $nW.kg-1)=222.42\pm42.42SD$ for the Rono and $169.03\pm34.52SD$ for the Bombinal. With more massive thigh muscles and greater mechanical power, the ranids would generate greater total power and thus higher energy release per unit time to muscle tissues for the burst take-off. As a consequence, biomechanical properties seen in the ranids seem to be more effective for frost take-off than in the Bombina.

• Ocean Systems Engineering
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• 제2권4호
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• pp.297-314
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• 2012

Power-take-off through inner dynamic system inside a floating buoy is suggested. The power take-off system is characterized by mass, stiffness, and damping and generates power through the relative heave motion between the buoy and inner mass (magnet or amateur). A systematic hydrodynamic theory is developed for the suggested WEC and the developed theory is illustrated by a case study. A vertical truncated cylinder is selected as a buoy and the optimal condition of the inner dynamic system for maximum PTO (power take off) through double resonance for the given wave condition is systematically investigated. Through the case study, it is seen that the maximum power can actually be obtained at the optimal spring and damper condition, as predicted by the developed WEC theory. However, the band-width of high performance region is not necessarily the greatest at the optimal (maximum-power-take-off) condition, so it has to be taken into consideration in the actual design of the WEC.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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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.

• 대한조선학회논문집
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• 제44권5호
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• pp.534-541
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• 2007

This paper suggests the mathematical method for the estimation of the required engine output for WIG crafts. The engine size of a WIG craft Is a key parameter in the design stage, because WIGs should overcome the hump drag during the take-off. Therefore, it is very important for a WIG designer to estimate required power and state change during take-off. The mathematical method was developed based on the steady planing state model of a planing boat. Through numerical calculations on various take-off states, it was found that the suggested method could give reasonable estimation of required power and state change during take-off.

• 한국산업융합학회 논문집
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• 제26권4_2호
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• pp.639-648
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• 2023

In modern society, UAM (Urban Air Mobility) transportation system is being developed as an alternative to urban traffic congestion and environmental problems, and electric vertical take-off and landing (eVTOL) is a combination of vertical take-off and landing function and electric power. It is attracting attention as an innovative next-generation transportation method as an eco-friendly alternative that reduces noise and air pollution by providing efficient mobility within the city. Since eVTOL development requires designing and implementing airframes suitable for various mission purposes, the power system needs to be developed as a platform concept before airframe development. In this study, we empirically proposed a test bench concept equipped with a stable power supply and an efficient control system, essential in developing a power platform with a combined function in the form of a fuselage and module type specialized for various mission purposes. The proposed drivetrain platform test bench consists of a system verifying the stable take-off and landing software and a power platform adjusting the motor's thrust. It will serve as a verification system that can be developed.

• Ocean Systems Engineering
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• 제4권1호
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• pp.63-82
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• 2014

Declutching control is applied to a hemispherical wave energy converter with direct linear electric Power-Take-Off systems oscillating in heave direction in both regular and irregular waves. The direct linear Power-Take-Off system can be simplified as a mechanical spring and damper system. Time domain model is applied to dynamics of the hemispherical wave energy converter in both regular and irregular waves. And state space model is used to replace the convolution term in time domain equation of the heave oscillation of the converter due to its inconvenience in analyzing the controlled motion of the converters. The declutching control strategy is conducted by optimal command theory based on Pontryagin's maximum principle to gain the controlled optimum sequence of Power-Take-Off forces. The results show that the wave energy converter with declutching control captures more energy than that without control and the former's amplitude and velocity is relatively larger. However, the amplification ratio of the absorbed power by declutching control is only slightly larger than 1. This may indicate that declutching control method may be inapplicable for oscillating wave energy converters with direct linear Power-Take-Off systems in real random sea state, considering the error of prediction of the wave excitation force.

• Ocean Systems Engineering
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• 제7권2호
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• pp.89-106
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• 2017

The study explores a novel design of wave energy converter (WEC) that utilizes the interaction between an inside heaving vertical cylinder with an outside fixed hollow cylinder. This design originates from the oscillating water column (OWC) type WEC but replaces the pneumatic power take off (PTO) through the Wells turbine with the hydrodynamic PTO through the inside heaving cylinder. To effectively evaluate the maximum power output, the system has been modeled in the hydrodynamic software AQWA (developed by ANSYS Inc) that has accumulated extensive offshore industry users. Ranges of the PTO parameters have been examined to make sure that proper linear damping can be implemented to simulate the PTO force. Comparing the efficiency of the pneumatic PTO with the hydrodynamic PTO, it appears that the hydrodynamic PTO is more promising than the traditional Wells turbine for an OWC system.

• 전기전자학회논문지
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• 제23권3호
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• pp.994-1002
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• 2019

본 논문은 농업용 전기차량의 전기식 동력인출장치용 전력변환시스템에 대해 제안한다. 대부분의 전기식 동력인출장치(Electric Power Take-Off : e-PTO)는 상용전원 $220V_{AC}$를 사용한다. 농업용 전기차량의 낮은 배터리 전압을 사용하여 높은 출력 전압을 공급하기 위한 DC-DC 컨버터와 DC-AC 인버터로 구성된 2단 구조를 갖는 양방향 전력변환시스템이 적합하다. 제안하는 전력변환시스템은 1단의 Dual Active Bridge(DAB)컨버터와 2단의 양방향 풀 브릿지 인버터로 구성된다. 또한, 초기 구동시 DC 버스단 커패시터 충전에 의해 발생되는 돌입 전류 저감을 위해 소프트 스타트 알고리즘을 제안한다. 3kW급 전력변환시스템 시제품 및 알고리즘을 구현하고 실험을 통해서 실용성을 입증하였다.

• 한국산학기술학회논문지
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• 제16권9호
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• pp.6297-6304
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• 2015

우리나라 최초의 원자력발전소인 고리 원전 1호기의 폐쇄가 결정됨에 따라 원전 해체가 화두가 되고 있다. 원전 해체는 우리나라에서 한번도 경험해 보지 못한 일로 해체 과정도 어렵고 시간도 많이 소요된다. 그 일부분인 해체물량 또한 파악이 어렵다. 본 연구에서는 최근 건설산업에 많이 활용되고 있는 BIM 기술을 원전 해체 물량산출에 활용할 수 있는 방안을 제시하였다. 그 결과, 원전 해체 공법선정 및 공정 확립, BIM 모델링 환경 준비, 작업분류체계 구축, 객체분류체계 구축, BIM 통합모델 작성, BIM 객체에 물량 속성 배분 등의 방안을 제시하였다. 제시한 방안은 영구정지 대상 원전이 집중적으로 발생하는 시기부터 유용하게 활용될 수 있다. 이에 기반한 기술확보를 통해 나아가 해외 원전 해체 사업 수주에도 유리하게 작용할 것으로 기대된다.