• Tribology and Lubricants
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• 제30권4호
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• pp.205-211
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• 2014

Recent studies emphasize the importance of pivot stiffness in the analysis of tilting pad bearings (TPBs). The present paper develops a finite element model of the pad pivot and compares the predicted pivot stiffness to the results of Hertzian contact model calculations. Specifically, a finite element analysis generates tetrahedral mesh models with ~40,000 nodes for a ball-socket pivot and ~50,000 nodes for a rocker-back pivot. These models assume a frictionless boundary condition in the contact area. Increasing the applied loads on the pad in conjunction with increasing time steps ensures rapid convergence during the nonlinear numerical analysis. Predictions are performed using the developed finite element model for increasing the differential diameters between the pad pivot (or ball) and the bearing housing (or socket). The predictions show that the pivot contact area increases with decreasing differential diameters and increasing applied loads. Further, the maximum deformation occurring at the pivot center increases with increasing differential diameters and increasing applied loads. The pivot stiffness increases nonlinearly with decreasing differential diameters and increasing applied loads. Comparisons of results of the developed finite element model to those of Hertzian contact model calculations assuming a small contact area show that the latter model underestimates the pivot stiffnesses predicted by the finite element models of the ball-socket and rocker-back pivots, particularly for small differential diameters. This result implies the need for cautionduring the design of pivot stiffness by the Hertzian contact model.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1016-1021
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• 2004

The need for developing a mathematical model for pad-pivot friction in tilting pad proceeding bearings has been well-recognized, since previous experimental work about the performances of the bearings hypothesized that the friction in the bearings is closely related to their performances. Especially, the sliding friction between pad and pivot in the ball and socket type of the bearings can influence the performance of the bearing. We propose a mathematical model for pad-pivot friction in the ball and socket type, which considers the geometrics of the pad and pivot of the bearings, by assuming the sliding friction in the ball and socket bearing as Coulomb friction. By utilizing the proposed model for pad-pivot friction, we show the analysis of Reynolds equation and energy equation, which explain the thermo-hydrodynamic characteristics of tilting pad proceeding bearings, by taking into account the turbulence and inlet pressure building as well. The results of the study show that the performance of titling-pad proceeding bearings can be greatly influenced by the pad-pivot friction. In particular, we have shown that the analysis of the pad-pivot friction is useful to explain the static proceeding loci and the dynamic characteristics of the ball and socket type of the bearings. Furthermore, for a given operating condition, we can obtain various equilibrium states which satisfy the static equilibrium conditions, by considering the pad-pivot friction.

• 대한한의학원전학회지
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• 제32권2호
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• pp.33-47
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• 2019

Objectives : To review the meaning of Open-Close-Pivot and its transition over time. Methods : Annotations and explanations in chapters where the theory of Open-Close-Pivot originated from in the "Suwen(素問)" and "Lingshu(靈樞)" were examined, followed by philological examination of key physicians. Results & Conclusions : Yang Shang Shan(楊上善) compared the 'Open-Close-Pivot' to a door. Wang Bing(王冰) explained it's movement and stillness to be the principle behind the Three-Yin-Three-Yang's threefold division. Wang Ji(汪機), in "XuSuwenChao(續素問鈔)" explained its physiological function as the entering and exiting of Ying Wei(營衛), and its scope to be exterior, interior, and center. Ma Shi(馬蒔) stratified it similar to "Shanghanlun(傷寒論)"'s six stages, while Wu Kun(吳崑) categorized Shaoyang(少陽) as being in-between exterior and interior. Zhang Jing Yue(張景岳) suggested a standard for the entering-exiting and exterior-interior-center concepts of the Open-Close-Pivot. Zhang Zhi Cong(張志聰) argued a theory of Open-Close-Pivot that emphasized the meaning of Three-Yin-Three-Yang, while Gao Shi Zong(高士宗) explained the relationship between Open, Close, Pivot and the functioning process. Shi Shou Tang(石壽棠) explained the physiology and pathology in the actions among Open-Close-Pivot with a focus on Pivot. Ke Qin(柯琴) applied Open-Close-Pivot to "Shanghanlun(傷寒論)" and used it as the basic principle to the Six Channel Ground Theory(六經地面說), also clinically applying it in the identification and treatment of the Six Channel patterns. Conclusions : Counting based word embedding methods seems to be more effective than.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2012년도 추계학술대회
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• pp.160-161
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• 2012

The traditional theory regarding the pivot point of a ship during maneuvering, so called apparent pivot point, is located nearly at 1/3 ship's length from the bow when the ship is moving ahead, and between 1/4 ship's length from the stern and the rudder post when going astern. The pivot point is sometimes considered to be the centre of leverage for forces acting on the ship. However, the pivot point is located out of ship due to strong lateral force, such as current and it is very inconvenient to use during maneuvering a ship. In this paper firstly, pivot points due to ship's condition are investigated carefully. And then the center of lateral resistance used at the present are determined. While a new lateral force is added, we can compare the pivot point with the center of lateral forces. Finally, we will suggest the center of all lateral forces for maneuvering instead of pivot point. Especially, it will be very helpful for pilots to handle ships in simulation.

• Journal of Advanced Marine Engineering and Technology
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• 제22권3호
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• pp.337-342
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• 1998

In this paper the lubrication performances of line pivoted pad thrust bearing and point pivoted pad thrust bearing are studied by a numerical analysis. The running characteristic parameters such as nondimensional load carrying capacity nondimensional friciton power loss nondimensional flow rate and film thickness ratios are calculated for various circumferential pivot positions. The results provide a usdful data for the selection of pivot position in a pivoted and thrust bearing.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.224-230
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• 2001

A numerical analysis for the gas lubricated flexure-pivot tilting pad journal bearing has been accomplished. The film pressure are obtained by Newton-Raphson method and the dynamic coefficients are evaluated by the pad assembly method. The effects of the pivot position of the pad on the static and dynamic characteristics are presented for three pads journal bearing with LBP. The optimum pivot positions for the static performance is different from that of the dynamic performance.

• 한국추진공학회지
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• 제9권4호
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• pp.73-80
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• 2005

유도무기의 추력방향 제어(Thrust Vector Control)를 위해 널리 운용되고 있는 가동노즐(Movable Nozzle)의 성능지표는 노즐의 회전중심(유효피봇)을 기준으로 결정된다. 그러나 유효피봇의 동특성으로 인해 실험이나 수학적으로 정확한 위치를 결정하기가 거의 불가능하다. 본 논문에서는 가동노즐 운동 특성을 ADAMS simulation 기법을 이용하여 파악하고 인공 신경망을 적용하여 유효 피봇을 추적할 수 있는 방법을 제안하였으며, 모사된 가상 가동노즐의 유효피봇 추적에 적용하여 만족스러운 결과를 얻음으로 벤취 실험이나 연소시험에 적용된 가동 노즐의 유효 피봇 추적에 활용 가능성을 제시하였다.

• Tribology and Lubricants
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• 제30권2호
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• pp.77-85
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• 2014

This study set out to predict the load capacity and rotordynamic coefficients of tilting-pad journal bearings, taking the pivot stiffness into account. The analysis uses rocker-back (cylindrical) and ball in socket (spherical) pivot models, both of which are based on Hertzian contact stress theory. The models ascertain the non-linear elastic deformation of the pivots according to the applied load, pivot geometry, and material properties. At present, the Reynolds equation for an isothermal, isoviscous, and incompressible fluid is used to calculate the film pressure by using the finite-element method, after which the Newton-Raphson method is used to simultaneously find the journal center location, pad angles, and pivot deflections. The bearing analysis, excluding the pivot models, is validated using predictions those are readily available in the literature. As the rotor speed increases, the predicted journal eccentricity and damping coefficients decrease, but the stiffness coefficients increase, as expected. Most importantly, the implementation of the pivot models increases the journal eccentricity but significantly decreases the stiffness and damping coefficients of the tilting-pad journal bearings.

• Journal of Advanced Marine Engineering and Technology
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• 제37권3호
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• pp.300-306
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• 2013

This paper presents a new method for constructing bilingual lexicons through a pivot language. The proposed method is adapted from the context-based approach, called the standard approach, which is well-known for building bilingual lexicons using comparable corpora. The main difference between the standard approach and the proposed method is how to represent context vectors. The former is to represent context vectors in a target language, while the latter in a pivot language. The proposed method is very simplified from the standard approach thereby. Furthermore, the proposed method is more accurate than the standard approach because it uses parallel corpora instead of comparable corpora. The experiments are conducted on a language pair, Korean and Spanish. Our experimental results have shown that the proposed method is quite attractive where a parallel corpus directly between source and target languages are unavailable, but both source-pivot and pivot-target parallel corpora are available.

• Korean Journal of Acupuncture
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• 제33권3호
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• pp.114-120
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• 2016

Objectives : It aims to establish a basic rule in Korean translation of the pathway of lung meridian in Miraculous Pivot Meridian vessel. Based on the rule, We tried to make standard translation of the pathway of lung meridian in Miraculous Pivot Meridian vessel. Methods : Books needed for this study were collected through searching Kyunghee University Library(http:// khis.khu.ac.kr). Keywords included "Miraculous Pivot of Huangdi's Internal Classic". We also include the book which is generally used as a textbook in Colleges of Korean Medicine. Results : In five Chinese books, the word-spacing was used differently in four phrases. Six Korean-translated books had the different translation in three phrases. We suggested a standard Korean translation of the pathway of lung meridian in Miraculous Pivot Meridian vessel. Conclusions : This result of the study would be expected to not only be published in Korean Journal of Acupuncture but be studied more about Korean translation by experts in this field.