• Title/Summary/Keyword: Encounter force

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A scientific approach to estimate the safe depth of burial of submarine pipelines against wave forces for different marine soil conditions

  • Neelamani, S.;Al-Banaa, K.
    • Ocean Systems Engineering
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    • v.3 no.1
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    • pp.9-34
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    • 2013
  • Submarine pipelines encounter significant wave forces in shallow coastal waters due to the action of waves. In order to reduce such forces (also to protect the pipe against anchors and dropped objects) they are buried below the seabed. The wave force variation due to burial depends on the engineering characteristics of the sub soil like hydraulic conductivity and porosity, apart from the design environmental conditions. For a given wave condition, in certain type of soil, the wave force can reduce drastically with increased burial and in certain other type of soil, it may not. It is hence essential to understand how the wave forces vary in soils of different hydraulic conductivity. Based on physical model study, the wave forces on the buried pipeline model is assessed for a wide range of wave conditions, for different burial depths and for four types of cohesion-less soils, covering hydraulic conductivity in the range of 0.286 to 1.84 mm/s. It is found that for all the four soil types, the horizontal wave force reduces with increase in depth of burial, whereas the vertical force is high for half buried condition. Among the soils, well graded one is better for half buried case, since the least vertical force is experienced for this situation. It is found that uniformly graded and low hydraulic conductivity soil attracts the maximum vertical force for half buried case. A case study analysis is carried out and is reported. The results of this study are useful for submarine buried pipeline design.

Unsteady galloping of sharp-edged bluff bodies: experimental observations on the effect of the wind angle of attack

  • Chen, Cong;Dai, Bingyu;Wieczorek, Niccolo;Unglaub, Julian;Thiele, Klaus
    • Wind and Structures
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    • v.35 no.4
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    • pp.255-268
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    • 2022
  • Light-weight or low-damped structures may encounter the unsteady galloping instability that occurs at low reduced wind speeds, where the classical quasi-steady assumption is invalid. Although this unsteady phenomenon has been widely studied for rectangular cross sections with one side perpendicular to the incidence flow, the effect of the mean wind angle of attack has not been paid enough attention yet. With four sectional models of different side ratios and geometric shapes, the presented research focuses on the effect of the wind angle of attack on unsteady galloping instability. In static tests, comparatively strong vortex shedding force was noticed in the middle of the range of flow incidence where the lift coefficient shows a negative slope. In aeroelastic tests with a low Scruton number, the typical unsteady galloping, which is due to an interaction with vortex-induced vibration and results in unrestricted oscillation initiating at the Kármán vortex resonance wind speed, was observed for the wind angles of attack that characterize relatively strong vortex shedding force. In contrast, for the wind angles of attack with relatively weak shedding force, an "atypical" unsteady galloping was found to occur at a reduced wind speed clearly higher than the Kármán-vortex resonance one. These observations are valid for all four wind tunnel models. One of the wind tunnel models (with a bridge deck cross section) was also tested in a turbulent flow with an intensity about 9%, showing only the atypical unsteady galloping. However, the wind angle of attack with the comparatively strong vortex shedding force remains the most unfavorable one with respect to the instability threshold in low Scruton number conditions.

Henry James's The Turn of the Screw: The Subject and the Ontological Status of the Real Gaze

  • Kim, Kyung-Soon
    • Journal of English Language & Literature
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    • v.57 no.6
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    • pp.999-1016
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    • 2011
  • In The Turn of the Screw, the go'erness encounters with the apparitions that harrow her throughout the story: she sees a frightening male ghost that Mrs. Grose identifies as Peter Quint, deceased former 'alet of the children's uncle, who had pre'iously shared the charge of the children with the pre'ious go'erness, Miss Jessel. The appearance of the ghosts hails the go'erness and thereby forces her to be jarred out of the comfortable habits of indi'iduality and plunged into a negati'ity de'oid of the socio-normati'e directi'es and guarantees. Such an encounter shows the idea that consciousness is a plenum of existence e'ocati'e of human mind as a decentered pandemonium. For the go'erness in The Turn of the Screw, the foundation to force her to experience the uncanny, as an inconsistency in the symbolic order, is particular. Its particularity is absolute in the same way e'ery one of us dreams his or her world. It resists mediation and cannot be made part of a symbolic medium. Just as Lacan's conceptions of desire, feminine sexuality, 'Object a,' not-whole, sla'ery, mastery, self-deception, authenticity, and act of psychoanalysis help us understand our contradictory social reality, so does The Turn of the Screw help us make sense of the way the go'erness, as the being who is capable of raising the question of being, questions the idea of being. In conclusion, the particular way the go'erness dreams her world is e'ocati'e of an excessi'e being, an anatomical complement, and a particular experience, such as the go'erness's encounter with the ghosts testifies to a knowledge that escapes the knowledge of the speaking being.

Beyond Words and Sounds: A Study on the Language of T. S. Eliot's Murder in the Cathedral (말과 소리 저 너머 -『대성당의 살인』의 언어고찰)

  • Kim, Han
    • Journal of English Language & Literature
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    • v.55 no.4
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    • pp.539-565
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    • 2009
  • T. S. Eliot attempted the combining of the liturgy of Anglican Church and a drama in Murder in the Cathedral (1935) and created a modern verse drama which comes most close to the regular tragedy like Greek tragedy today. Eliot chose the drama to deliver his religious insight because of its ritualistic origin and its potentiality to deliver a dramatic world which can contain a complete order. The central theme of this play is the martyrdom. The dramatic action of killing the archbishop Thomas Beckett in this play, however, is not treated as important event enough to be a dramatic climax. He is portrayed as a witness to the reality of God's will rather than a man who wills to give up his own life for any religious belief or cause. In Eliot, a martyr is nothing but "a witness" in its ancient sense. This paper purposes to review the language of this play. The various and new meters and rhythms of the language of this play function enough to bring its playwright to encounter 'the real audience' in 'a living theatre'. The interactions between different verbal models also play a big role to make this play a living theatre. Eliot found the poetry which crosses the various classes and levels of the tastes of audience is the most useful poetry. And the poetry of this play proves as the very thing which intensifies the theme of the play and gives the most powerful force to the play. Especially Eliot's poetry succeeds smost in the various and free meters of chorus, which makes Eliot the first playwright since Aeschylus, who could bring the chorus to undertake the function of extending the dramatic action of the play into the universal meaning. In the theatre the real audience identifies themselves with chorus. And the chorus leads the audience to respond to peace which passeth understanding beyond words and sounds of this play, which is the desired response in Eliot's conception of drama.

THE SMOOTHED PARTICLE HYDRODYNAMICS AND THE BINARY TREE COMBINED INTO BTSPH: PERFORMANCE TESTS

  • KIM W. -T.;HONG S. S.;YUN H. S.
    • Journal of The Korean Astronomical Society
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    • v.27 no.1
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    • pp.13-29
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    • 1994
  • We have constructed a 3-dim hydrodynamics code called BTSPH. The fluid dynamics part of the code is based on the smoothed particle hydrodynamics (SPH), and for its Poisson solver the binary tree (BT) scheme is employed. We let the smoothing length in the SPH algorithm vary with space and time, so that resolution of the calculation is considerably enhanced over the version of SPH with fixed smoothing length. The binary tree scheme calculates the gravitational force at a point by collecting the monopole forces from neighboring particles and the multipole forces from aggregates of distant particles. The BTSPH is free from geometric constraints, does not rely on grids, and needs arrays of moderate size. With the code we have run the following set of test calculations: one-dim shock tube, adiabatic collapse of an isothermal cloud, small oscillation of an equilibrium polytrope of index 3/2, and tidal encounter of the polytrope and a point mass perturber. Results of the tests confirmed the code performance.

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Development of Technology for Printing Pressure Control of Blanket Cylinder (블랭킷 실린더의 인압제어 기술개발)

  • Ham, Yeong-Bok;Yun, So-Nam;Kim, Gwang-Yeong;Choe, Byeong-O
    • 연구논문집
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    • s.32
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    • pp.15-22
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    • 2002
  • In offset or intaglio printing machine, it's operated with combination of blanket cylinder and impression cylinder. The blanket cylinder has some number of grooves to attach the blanket on surface. In case of operating the printing machine, it has generate mechanical impact noise when the two cylinders encounter with the grooves. So, in this study, we developed a printing pressure control algorithm with hydraulic servo control system. We also proposed simulation model of experimental device to analysis the throw on force response of hydraulic servo actuator. Finally, we have reduced the mechanical impact noise and improved printing quality with a groove detecting signal and PI control of hydraulic servo actuator.

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An esthetic appliance for the management of crown-root fracture: a case report

  • Jeon, Sang-Min;Lee, Kang-Hee;Jung, Bock-Young
    • Restorative Dentistry and Endodontics
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    • v.39 no.3
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    • pp.226-229
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    • 2014
  • Orthodontic extrusion is usually performed by means of a fixed orthodontic appliance that utilizes arch wire attached to adjacent teeth and transfers the desired force by elastic from the wire to the root. However, clinicians often encounter cases where the bonding required for tooth traction is not possible because the adjacent teeth have been restored with ceramic or veneer. The purpose of this case report is to describe a modified orthodontic extrusion appliance that is useful when conventional orthodontic treatment is not possible. The modified appliance was fabricated using an artificial tooth, clear plastic sheeting, and a braided fiber-reinforced composite strip that covered adjacent teeth without bonding. It satisfied the esthetic and functional needs of the patient and established the optimal biologic width.

A Force Reflecting and Compliant Control for Heavy-Duty Power Telemanipulators with Control Input Saturation (제어입력 포화를 고려한 고하중 원격조작기의 힘반영 유연성 제어)

  • An, Seong-Ho;Yun, Ji-Seop;Lee, Sang-Jeong
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.37 no.5
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    • pp.22-33
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    • 2000
  • Since the heavy-duty power manipulator generally has high ratio gear reducers at its joints, its dynamic characteristics is much slower than that of the master manipulator and it is likely to encounter the saturation in the input magnitude when it is used as the slave manipulator in telemanipulation systems. This paper proposes a force reflecting and compliant control scheme for the heavy-duty power telemanipulator. The main advantage of the proposed scheme is that it provides a precise position and compliant control performance for a telemanipulator with control input saturation. The stability of the proposed scheme is analyzed and a series of experiments shows its performance.

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Current Effect on the Motion and Drift Force of Cylinders Floating in Waves (주상체(柱狀體)의 운동(運動) 및 표류력(漂流力)에 미치는 해류(海流)의 영향(影響))

  • Sei-Chang,Lee
    • Bulletin of the Society of Naval Architects of Korea
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    • v.23 no.4
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    • pp.25-34
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    • 1986
  • A two-dimensional linear method has been developed for the motion and the second-order steady force arising from the hydrodynamic coupling between waves and currents in the presence of a body of arbitrary shape. Interaction between the incident wave and current in the absence of the body lies in the realm beyond our interest. A Fredholm integral equation of the second kind is employed in association with the Haskind's potential for a steadily moving source of pulsating strength located in or below the free surface. The numerical calculations at the preliminary stage showed a significant fluctuation of the hydrodynamic forces on the surface-piercing body. The problem is approximately solved by using the asymptotic Green function for $U^2{\rightarrow}0$. The original Green function, however, is applied for the fully submerged body. Numerical calculations are made for a submerged and for a half-immersed circular cylinder and extensively for the mid-ship section of a Lewis-form. Some of the results are compared with other analytical results without any available experimental data. The current has strong influence on roll motion near resonance. When the current opposes the waves, the roll response are generally negligible in the low frequency region. The current has strong influence on roll motion near resonance. When the current opposes the wave, the roll response decreases. When the current and wave come from the same direction, the roll response increases significantly, as the current speed increases. The mean drift forces and moment on the submerged body are more affected by current than those on the semi-immersed circular cylinder or on the ship-like section in the encounter frequency domain.

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Gloria Naylor's Linden Hills: A Tragic Saga of the Oppressive "Primal Scene" and Deformed "Family Romance" (글로리아 네일러의 『린덴 힐즈』 -억압적 '원장면'과 왜곡된 '가족 로맨스'의 비극)

  • Hwangbo, Kyeong
    • Journal of English Language & Literature
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    • v.58 no.1
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    • pp.21-42
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    • 2012
  • Gloria Naylor's second novel Linden Hills (1985) explores the issues of self-exploration, empowerment, history, and memory by delineating the communal and familial tragedies and the distortion of values prevalent in a prosperous African-American urban community called Linden Hills. Drawing upon the Freud's concept of "primal scene" and "family romance," this paper aims to focus upon the Nedeed family, the founder of Linden Hills, and investigate the compelling traumatogenic force within the family, which is inseparably intertwined with the inversion of values and moral corruption permeating the entire community. The "primal crime" committed by the Nedeed ancestors serves to preserve and perpetuate a tyrannical rule by ruthless patriarchs who reign by underhanded strategies of purposefully neglecting and abusing others, including their own wives. The imprisonment, by Luther Nedeed, of his wife Willa in the family morgue epitomizes the long legacy running in the family-the oppression and burial of the pre-Oedipal, maternal history. Willa's accidental encounter, at the nadir of the family estate and her personal despair, with the faded records of the forgotten and abused Nedeed women exposes the violence-ridden ground of the family's primal scene and the absurdity of family romance the Nedeeds pursued. As the several lines of poem composed by Willie, Willa's male double, show, the hidden, forgotten history of the Nedeed women, in a sense, is the real, which cannot be assimilated to the social symbolic governed by the inhumane patriarchy of the Nedeed family and the success-oriented Linden Hills society. By portraying a catastrophic downfall of the Nedeed family and the futile outcome of its family romance, the ending of Linden Hills conveys implicitly that the contingent symbolic order and its oppressive control, however solid and invincible they may seem, can be toppled down by the real, its nameless forgotten Other.