• 농업과학연구
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• 제49권4호
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• pp.677-696
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• 2022

Development of radish collectors may enhance radish production and promote upland crop mechanization in the Republic of Korea. Theoretical analysis of power is crucial to ensure the optimum design of agricultural machinery. The aim of the present study is to analyze theoretically the power requirement of a tractor-mounted radish collector under development and to propose design guidelines. The important components of the radish collector were belt-type conveyors, three hydraulic motors, and a direct current (DC) winch motor to operate the total radish collecting process. Theoretical equations were used to calculate the hydraulic motor's power, winch motor power, and draft power at loaded and unloaded conditions. A variety of tractors (44 - 74 kW) and different soil characteristics (hard, firm, tilted, and sandy) were considered to investigate the appropriate drawbar power. Variations of the power requirement of the tractor-mounted radish collector were observed due to modifications of the design parameters. The required hydraulic power of the stem cutting conveyor, stem cutting blade, and transfer conveyor of the radish collector were 0.23 and 0.24, 0.18 and 0.19, and 0.19 and 0.22 kW under unloaded and loaded conditions, respectively. The maximum draft power was calculated as 0.89, 1.07, 1.25, and 1.61 kW at a 30° tilted angle for hard, firm, tilted, and sandy soil, respectively. The calculation showed 2.07 kW DC power was required for unfolding or folding the stem-cutting conveyor. A maximum power of 4.78 kW was prescribed for conducting the whole process of the tractor-mounted radish collector. The analysis of power introduced in this study will be helpful to select the appropriate design parameters for the successful development of a tractor-mounted radish collector.

• 전기저널
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• 5호통권149호
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• pp.8-13
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• 1989

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.1043-1052
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• 1993

Field experiments were conducted to determine the optimum combination of performance parameters of a single-shank, tractor-mounted oscillating subsoiler. Tests were conducted at frequencies of oscillation of 3.7 , 5.67, 7.58, 9.48 and 11.456Hz ; amplitudes of 18, 21, 23.5, 34 and 36.5 mm ; and forward speeds of 1.84, 2.19 and 3.42 kmph at moisture content close to the plastic limit of the soil. It was observed that there was a reduction in average draft but an a increase in average total power requirement for oscillating than non-oscillating subsoiling. The draft and power ratios were significantly affected by the forward speed, frequency and amplitude. Their combined interaction expressed in terms of the velocity ratio parameter( the ratio of peak tool velocity and forward speed) however has the strongest influence. At the same velocity ratio, the draft reduction and power increase were less at higher amplitude of oscillation . As the oscillating frequency is increased toward the soil resonance the draft requirement becomes less. For the field conditions tested. the optimum operation was obtained at an amplitude of 36.5mm, frequency of 9.48Hz and speed of 2.19 kmph with a draft ratio of 0.33 and a power ratio of only 1.24.

• International Journal of Aerospace System Engineering
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• 제9권1호
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• pp.1-15
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• 2022

Pyrotechnic initiators provide a source of pyrotechnic energy used to initiate a variety of space mechanisms. Pyrotechnic systems build in electromagnetic environment that may lead to critical or catastrophic hazards. Special precautions are need to prevent a pulse large enough to trigger the initiator from appearing in the pyrotechnic firing circuits at any but the desired time. The EMC verification shall be shown by analysis or test that the pyrotechnic systems meets the requirements of inadvertent activation. The MIL-STD-1576 and two range safeties, AFSPC and CSG, require the safety margin for electromagnetic potential hazards to pyrotechnic systems to a level at least 20 dB below the maximum no-fire power of the EED. The PC23 is equivalent to NASA standard initiator and the 1EPWH100 squib is ESA standard initiator. This paper verifies the two safety margins for electromagnetic potential hazards. The first is verified by analyzing against a RF power. The second is verified by testing against a DC current. The EMC safety margin requirement against RF power has been demonstrated through the electric field coupling analysis in differential mode with 21 dB both PC23 and 1EPWH100, and in common mode with 58 dB for PC23 and 48 dB for 1EPWH100 against the maximum no-fire power of the EED. Also, the EMC safety margin requirement against DC current has been demonstrated through the electrical isolation test for the pyrotechnic firing circuits with greater than 20 dB below the maximum no-fire current of the EED.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.189-192
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• 2003

Electrical power in satellite system should persistently satisfy specified power requirement even though that happen the failure of solar array string or battery cell during the mission operation. In this study, the solar array and battery of GEO Communication Satellite with 3kW capacity are designed, and energy balance analysis according to power operation mode are performed to meet specified power capacity at the transfer orbit

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.802-807
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• 1998

The main drawback of parallel type active power filters (APF) is the large capacity required for harmonic compensation. This paper evaluates the APF capacity requirement of harmonic/reactive power compensation for thyristor converter load. Theoretically achievable maximum power factor under partial load is evaluated. And it is shown that the APF capacity can be considerably reduced while slightly sacrificing the filtering performance by deliberately limiting the peak current of the APF.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.295-297
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• 2003

Cryogenic systems is requirement for the operation of HTS power cables. In general, HTS power cables require temperature below 77K, a temperature that can be achieved from the liquid nitrogen or sub-cooled LN2. HTS power cable is needed for sufficient refrigeration to overcome its low temperature heat loading. This loading typically comes in two forms : (1) heat leaks from the surroundings and (2) internal heat generation. This paper is a explanation for the cooling test of 10m HTS power cable.

• 물과 미래
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• 제26권1호
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• pp.63-69
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• 1993

매립이 완료된 Landfills이나 오염된 지하수의 오염물질을 제거하여 다른 용도로 재사용하는 기술이 오늘날 중요한 문제로 대두되고 있다. 진동을 이용하여 제가효율을 높히는 방법은 요즘 흔히 사용되고 있는 방법중의 하나이다. Ultrasonic의 효과를 사용함으로써, 기계적인 제거효과가 대단하다는 것은 이미 몇몇 연구자들에 의해 확인된바 있다. 이 연구에서는 Probe-Type Lutrasonic Processor를 사용하여 Clayey-Sand Chamber를 가지고 실험을 해보았다. 실험중 계속적인 Pumping과 함께 Ultrasonic을 작동시킨 결과, Clayey 입자들의 분리 및 제거에 큰 효과를 얻었으며, 그로 인하여 투수계수가 크게 증가하는 효과를 보았다. 또한, 실험 전과 후의 입자크기의 분포도가 크게 변했는데, 그 이유는 Ultrasonic의 진동효과 때문이다. 실험결과, 0.004mm 이하의 입자들은 Ultrasonic의 효과에 의해 Mobilize되었으며, 0.04-1.0mm의 입자는 부서져서 작은 입자로 되었다. 이 기구를 사용하기 위한 유지비와 전력비등을 고려하여 이 기구의 실용성을 검토해 보았다. 필요한 Power를 위해 요구되는 전력의 양은 깊이에 의한 대상 site의 응력, 온도, 그리고 Fuid의 Viscosity에 의해 좌우되며, 그중 가장 큰 영향을 미치는 요소는 흙의 깊이이다. 여러 가지의 다른 깊이에서의 경제적인 실용성을 1.0, 2.0in 직경의 Horn Sonicator를 사용했을 경우에 대하여 비교와 분석을 하였다.

• 원자력산업
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• 8호
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• pp.35-52
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• 1978

The geologically favourable areas for the occurrence of uranium in Australia and the geology of the major deposits are discussed as well as exploration programs and expenditures. Australis has no short-term requirement for nuclear power generation and its

• 동력기계공학회지
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• 제20권1호
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• pp.63-68
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• 2016

The study is arranged in the form of plate-shaped in the Apartment Houses with placed at right angles. After examined the daylight environment and the indoor illumination in this form of Apartment Houses, in order to improve the daylight environment of the lower floors, I examined the daylight environment. In order to match the indoor illumination, as a standard illumination 400lx, I examine the necessary lighting energy based on the direction and time for the different parts in the Apartment Houses, As the first floor, the lowest power requirement appeared to the South(457W), and the most power requirement appeared to the East(843W).