• Title, Summary, Keyword: End effect

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Effect of a Number of Organic Sources on the Ammonification and Nitrification of Urea and Soil Reaction (요소의 암모니아화 및 질산화와 토양반응에 미친 수종 유기물의 영향)

  • 오왕근;허지희;김재영
    • Asian Journal of Turfgrass Science
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    • v.5 no.1
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    • pp.47-53
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    • 1991
  • A laboratory experiment was conducted in order to learn the effect of a number of organic matters on the ammonification and nitrification of urea, and the reaction of soil, applied to a loamy upland soil poor in orgnic matter(<1.5%, without plants 1.The ammonification of urea was most pronounced in one week period immediatly after fertilizer and water treated, after which a rapid decrease of it was followed showing no accumulation at the end of 3rd week. Owing to the accumlation of ammonium, pHs of treated soils were read 7.0 to 7.3 from 6.8~6.9. 2.Nitrification was also progressed rapidly in the first one week period so that the accumulation of NO$_3$-N surpassed that of ammonia during this period. After the 1st week the accumulation of N0$_3$-N was continuously increased showing the maximum at the end of 4 weeks following a sharp decrease at the end of 5th weeks. The accumulation of NO$_3$-N dropped soil pH from 6.8-7.0 to 6. 0-6.2,but the decrease of NO-N at the end of 5th weeks brought up soil pH to 6.4-6.6. again. 3.Amino acid fermentation byproduct rich in salt, paticularly chloride, slowed down the ammonification and nitrification of urea. 4.The application of organic matter diminished the acidifying effect of chemical fertilizers. The diminishing effect of soluble humic acid and amion acid fermentation byproduct showed greater than that of solid organic matter in this experiment, which might be own to the application of a rather small amount of water soluble organic matters. Rice straw powder among solid organic matters appeared to be the least in the diminishing effect above. It may be reasoned that these soluble organic matters decomposes rapidly so as to affect Soil pH, but solid organic matters, particularly the rice straw powder, form acidic humus.

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Study On The Travelling Magnetic Field In The Linear Induction Motor With Its End Effect Taken Into Consideration (유도형 Linear Motor의 단부효과를 고려한 이동자계에 관한 연구)

  • Dal Ho Im
    • 전기의세계
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    • v.21 no.4
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    • pp.7-14
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    • 1972
  • The author has established a general equation for the travelling magnetic field in air gap with the end effect taken into consideration, which constitutes the basics for the analysis of characteristics of linear induction motor. This equation is verified by comparison of the experimental values with the theoretically calculated values. The properties of the travelling wave with attenuation, which is contained in the travelling magnetic field of linear induction motor, have been verified, and consequently the practicable equation is established with these effects taken into consideration. This provides the solid foundation for the theoretical analysis of the characteristics of the linear induction motor.

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Direct Thrust Control Response of Linear Induction Motor with Cage-type Secondary Considering End Effect (단부 효과를 고려한 농형 2차측을 갖는 선형 유도전동기의 직접 추력 제어 응답 특성 고찰)

  • Kim, Kyung-Min;Park, Seung-Chan
    • Proceedings of the KIEE Conference
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    • pp.15-17
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    • 2003
  • In this paper, direct thrust control(DTC) scheme is applied to a linear induction motor(LIM) with cage-type secondary. The line voltages and phase currents are detected and a thrust correction coefficient considering the end effect of the LIM is introduced in order to Improve the accuracy of thrust estimation in the DTC implementation. Experimental results for thrust and flux responses are presented.

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Effect of Free End Shape on Wake Structure Around a Finite Cylinder Located in an Atmospheric Boundary Layer (대기경계층 내에 놓인 실린더의 자유단 형상변화가 후류유동에 미치는 영향에 관한 연구)

  • Park, Cheol-Woo;Lee, Sang-Joon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.1
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    • pp.105-116
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    • 2003
  • The flow structure around the free end of a finite circular cylinder (FC) embedded in an atmospheric boundary layer (ABL) over open terrain was investigated experimentally with varying the free end shape. The experiments were carried out in a closed-return type subsonic wind tunnel. A finite cylinder with an aspect ratio (L/D) of 6 was mounted vertically on a long flat plate. The Reynolds number based on the cylinder diameter is about Re=7,500. The velocity fields near the FC free end were measured using the single-frame double-exposure PIV method. As a result, for the FC with a right-angled free end, there is a peculiar vortical structure, showing counter-rotating twin vortices near the FC free end. It is caused by the interaction between the entrained irrotational fluids from both sides of FC and the downwash flow from the FC free-end.

Influence of Spring Constant and Tip Mass at Free End on Stability of Timoshenko Cantilever Column subjected to a Follower Force (자유단의 스프링 상수와 부가 말단질량이 종동력을 받는 Timoshenko 외팔보의 안정성에 미치는 영향)

  • 손종동
    • Journal of the Korean Society of Safety
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    • v.13 no.4
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    • pp.49-58
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    • 1998
  • On the stability of the Timoshenko cantilever column subjected of a compressive follower force, the influences of the moment of inertia of the tip mass at the free end and the characteristics of a translational spring at the free end of the column are studied. The equations of motion and boundary conditions of system are estabilished by using the d'Alembert virtual work of principle. On the evaluation of stability of the column, the effect of the shear deformation and rotatory inertia is considered in calculation. The moment of inertia of the tip mass at the free end of the column is changed by adjusting the distance c, from the free end of the column to the tip mass center. The free end of the column is supported elastically by a translational spring. For the maintenance of the good stability of the column, it is also proved that the constant of the translational spring at the free end must be very large for the case without a tip mass while it must be small for the case with a tip mass. Therefore, it is found that the shape of the tip mass and the characteristic of the spring at the free end are very effective elements for the stability of the column when the columns subjected to a compressive follower force are designed.

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A Study on the Measurement of End Bearing Capacity for Large Diameter Drilled Shaft Constructed in Fault Zone Using the Static Bi-directional End Leading Test (양방향 선단재하시험을 이용한 단층파쇄대에 시공된 대구경 현장타설말뚝의 선단지지력 측정 연구)

  • 정창규;정성민;황근배;최용규
    • Journal of the Korean Geotechnical Society
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    • v.20 no.5
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    • pp.135-143
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    • 2004
  • In the land section of marine bridge construction site, to confirm the end bearing of large diameter drilled shaft constructed in the fault zone which was discovered unexpectedly, the hi-directional end loading tests were performed. The objectives of this study are to confirm the end bearing of the pile constructed in fault zone and the increasing effect of end bearing after grouting the base ground beneath the pile toe. After grouting the pile base ground, the settlement of pile base decreased considerably and the pile base resistance increased more than twice.

Shaking Motion Characteristics of a Cod-end Caused by an Attached Circular Canvas during Tank Experiments and Sea Trials

  • Kim, Yonghae
    • Fisheries and aquatic sciences
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    • v.16 no.3
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    • pp.211-220
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    • 2013
  • A shaking motion could be used to improve fish escapement from a cod-end net by creating a sieving effect over the swept volume or by disturbing the optomotor response of the fish. In this study, a perpendicular shaking motion was generated in a towed cod-end net by a circular canvas attached to the end of the codend, which formed a biased cap-like shape. This concept was tested by using a model in a flow tank and by towing a prototype cod-end during sea trials. For the model tests, the amplitude of the shaking motion was $0.6{\pm}0.1$ times the rear diameter of the cod-end, and the period of the shaking motion was $2.6{\pm}0.1$ s at a flow velocity of 0.6 or 0.8 m/s. In the sea trials, the amplitude was $0.5{\pm}0.2$ times the rear diameter of the cod-end, and the period of the shaking motion was $7{\pm}4$ s at towing speeds of 1.2 or 1.7 m/s. Thus, the shaking amplitude during the sea trials was equal to or less than that observed in the tank tests, and the shaking period was twice as long. The shaking motion described by the amplitude and period could be an effective means to stimulate fish escapement from cod-end during fishing operations considering the response of the fish.