• Title/Summary/Keyword: gravity center

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Detailed Finite Element Analysis of Full-scale Four-story Steel Frame Structure subjected to Consecutive Ground Motions

  • Tagawa, Hiroyuki;Miyamura, Tomoshi;Yamashita, Takuzo;Kohiyama, Masayuki;Ohsaki, Makoto
    • International Journal of High-Rise Buildings
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    • v.4 no.1
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    • pp.65-73
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    • 2015
  • Detailed finite element (FE) analyses of a full-scale four-story steel frame structure, subjected to consecutive 60% and 100% excitations from the JR Takatori records during the 1995 Hyogoken-Nanbu earthquake, are conducted using E-Simulator. The four-story frame was tested at the largest shake-table facility in the world, E-Defense, in 2007. E-Simulator is a parallel FE analysis software package developed to accurately simulate structural behavior up to collapse by using a fine mesh of solid elements. To reduce computational time in consecutive dynamic time history analyses, static analysis with gravity force is introduced to terminate the vibration of the structure during the analysis of 60% excitation. An overall sway mechanism when subjected to 60% excitation and a story mechanism resulting from local buckling of the first-story columns when subjected to 100% excitation are simulated by using E-Simulator. The story drift response to the consecutive 60% and 100% excitations is slightly smaller than that for the single 100% excitation.

Design and Assessment of an Oil-treatment Process for Bitumen Separation (비투멘 유체 분리를 위한 오일처리공정의 설계와 평가)

  • Jeong, Moon;Lee, Sang-Jun;Shin, Heung-Sik;Jo, Eun-Bi;Hwang, In-Ju;Kang, Choon-Hyung
    • The KSFM Journal of Fluid Machinery
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    • v.19 no.3
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    • pp.5-9
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    • 2016
  • The purpose of this paper is to define criteria to be used as part of the engineering design for an oil sands plant equipped with the steam assisted gravity drainage process. In this effort, the oil treatment process of an oil sands plant on a pilot scale was focused for detailed investigation. The thermodynamic properties of the process fluid, which is mainly composed of bitumen and water, were estimated with the CPA model. The commercial tool aspen HYSYS was used for the analysis throughout this work along with the provided input data and some necessary assumptions. From the simulation results, the heat and mass balances for a 300 BPD plant were established in order to define standard data for its modular design. In particular, the basis of design for equipment size, heat transfer areas, capital cost and operation cost was extensively discussed.

Muscle Tone and Somatosensory System acting on This (근육긴장도와 이에 영향을 미치는 체성감각계에 관한 고찰)

  • Kim Joong-Hwi;Kwon Yong-Hyun;Park Jung-Mi;Kim Chung-Sun
    • The Journal of Korean Physical Therapy
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    • v.15 no.2
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    • pp.85-99
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    • 2003
  • Muscle tone is the force with which a muscle resists being lengthened. Muscle tone is often tested clinically by passively extending and flexing a relaxed patient's limbs and feeling the resistance offered by the muscle. Both nonneural and neural mechanism contribute to muscle tone. Muscle tone is the mechanisms that contribute to the generation of tone in individual muscles when a person is in a relaxed state. This background level of activity changes in a certain antigravity posture muscle when we stand upright, thus counteracting the force of gravity. This increased level of activity in antigravity muscles is known as postural tone. The evidence from experiments showing that lesions of the dorsal(sensory) roots of the spinal cord reduced muscle(postural) tone is influenced by inputs from the somatosensory system. Patients with neurological damage have several state of muscle(postural) tone, which display from flaccidity to rigidity. This review article deal with muscle tone and somatosensory system acting on this. The understanding about this contribute to a better therapeutic approach for the rehabilitation of patients to have an abnormal muscle(postural) tone due to neurological damage.

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Kinematical Analysis of the YEGA Motion on the Uneven Parallel Bars (이단 평행봉 YEGA 동작의 운동학적 분석)

  • Lee, Young-Sik
    • Korean Journal of Applied Biomechanics
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    • v.15 no.1
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    • pp.111-125
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    • 2005
  • This study was intended to assist athletes in having a technical understanding of the Yega motion and provide basic material for improving their competitive ability by analyzing the kinematic variable of the Yega motion during the competition of the uneven parallel bar of female gymnastics. For this purpose, the game of female gymnastics participating in the uneven parallel bar game was personally videotaped using the DLT(direct linear transformation) method. An attempt was made to make a comparative analysis of the Yega motion by dividing the final first to third places into the upper group('A' group) and the sixth to eighth places into the lower group('B' group). Based on the results of actual analysis on the scenes of actual game, the following conclusion was concluded: 1. Athletes in the 'A' group showed the shorter required time on the flight phase(P3) than counterparts in the 'B' group. 2. Athletes in the 'A' group showed the little width in the horizontal displacement of the center of gravity than counterparts in the 'B' group. But athletes in the 'A' group exhibited the somewhat greater relative vertical height of the center of the body. 3. Athletes in the 'A' group showed the greater resultant velocity at the lowest point of the center of the body(E2) and at the point in time of release(E3) compared to counterparts in the 'B' group.

A Study on Characteristics of Precession Motion for a Smart Munition (지능형 탄두의 세차운동 특성 해석 및 연구)

  • Ha, Do-Jun;Kim, Byoung-Soo;Kim, In-Keun;Song, Ho-In;Lee, Young-Jae
    • Journal of the Korea Institute of Military Science and Technology
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    • v.15 no.3
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    • pp.257-265
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    • 2012
  • This paper presents a study on characteristics of precession motion of a smart munition. It's a kind of the Sensor Fuzed Weapon. The particular thing for the smart munition is that it has precession motion in the air while the sensor is searching the ground to detect ground vehicles such as tanks. The smart munition has a cylindrical shape and has a sensor attached on its side. Due to its non-uniform mass distribution, its center of gravity(CG) is located away from the center of volume(CV). In order for the smart munition to detect the target effectively, the ground searching pattern of sensor should have an uniform circular form, and for this, the precession motion of smart munition should be in its steady-state. Finally, it is necessary to choose the right initial conditions at the moment of firing, for the steady-state precession motion during flight.

Least Squares Based PID Control of an Electromagnetic Suspension System

  • Park, Yon-Mook;Tahk, Min-Jea;Nam, Myeong-Ryong;Seo, In-Ho;Lee, Sang-Hyun;Lim, Jong-Tae
    • International Journal of Aeronautical and Space Sciences
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    • v.4 no.2
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    • pp.69-78
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    • 2003
  • In this paper, we develop the so-called functional test model for magnetic bearing wheels. The functional test model developed in this paper is a kind of electromagnetic suspension systems and has three degree of freedom, which consists of one axial suspension from gravity and the other two axes gimbaling capability to small angle, and does not include the motor. For the control of the functional test model, we derive the optimal electromagnetic forces based on the least squares method, and use the proportional-integral derivative controller. Then, we develop a hardware setup, which mainly consists of the digital signal processor and the 12-bit analog-to-digital and digital-to-analog converters, and show the experimental results.

Mixed Tumor in Deep Lobe and Versatility of Acellular Dermal Matrix

  • Byun, Jin Hwan;Lim, Jung Soo;Lee, Hye Kyung
    • Archives of Craniofacial Surgery
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    • v.18 no.2
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    • pp.132-136
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    • 2017
  • Frey's syndrome and infra-auricular depressed deformities are the ones of the most common complications that can occur after total parotidectomy. We report 1 case of pleomorphic adenoma occurred in the deep lobe that obtained good results from using acellular dermal matrix (ADM) after total parotidectomy. A 24-year-old man visited the hospital with oval shape mass in right mandibular angle which of 4 cm in size was found in the deep lobe of right parotid gland from Magnetic resonance imaging scanning and a pleomorphic adenoma was suspected. A total parotidectomy was performed while preserving the facial nerve. The material known as ADM were placed in the depressed part from where the mass was removed, and the site was sutured. The surgery site was healed well without any complications such as Frey's syndrome or infra-auricular depressed deformities. The pathological result was confirmed as pleomorphic adenoma. In addition to these advantages, it does not have little potential of deformation by the gravity after the surgery, and there is no restraint on circulation, which makes fabrication free and each deformation into various shapes can be described as another advantage of the reconstruction using the ADM.

Novel aspects of elastic flapping wing: Analytical solution for inertial forcing

  • Zare, Hadi;Pourtakdoust, Seid H.;Bighashdel, Ariyan
    • Advances in aircraft and spacecraft science
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    • v.5 no.3
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    • pp.335-348
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    • 2018
  • The structural dynamics (SD) behavior of Elastic Flapping Wings (EFWs) is investigated analytically as a novel approach in EFWs analysis. In this regard an analytical SD solution of EFW undergoing a prescribed rigid body motion is initially derived, where the governing equations are expressed in modal space. The inertial forces are also analytically computed utilizing the actuator induced acceleration effects on the wing structure, while due to importance of analytical solution the linearity assumption is also considered. The formulated initial-value problem is solved analytically to study the EFW structural responses, where the effect of structure-actuator frequency ratio, structure-flapping frequency ratio as well as the structure damping ratio on the EFW pick amplitude is analyzed. A case study is also simulated in which the wing is modeled as an elastic beam with shell elements undergoing a prescribed sinusoidal motion. The corresponding EFW transient and steady response in on-off servo behavior is investigated. This study provides a conceptual understanding for the overall EFW SD behavior in the presence of inertial forces plus the servo dynamics effects. In addition to the substantial analytical results, the study paves a new mathematical way to better understanding the complex role of SD in dynamic EFWs behavior. Specifically, similar mathematical formulations can be carried out to investigate the effect of aerodynamics and/or gravity.

An experimental study of the effect of mooring systems on the dynamics of a SPAR buoy-type floating offshore wind turbine

  • Hong, Sinpyo;Lee, Inwon;Park, Seong Hyeon;Lee, Cheolmin;Chun, Ho-Hwan;Lim, Hee Chang
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.3
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    • pp.559-579
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    • 2015
  • An experimental study of the effect of mooring systems on the dynamics of a SPAR buoy-type floating offshore wind turbine is presented. The effects of the Center of Gravity (COG), mooring line spring constant, and fairlead location on the turbine's motion in response to regular waves are investigated. Experimental results show that for a typical mooring system of a SPAR buoy-type Floating Offshore Wind Turbine (FOWT), the effect of mooring systems on the dynamics of the turbine can be considered negligible. However, the pitch decreases notably as the COG increases. The COG and spring constant of the mooring line have a negligible effect on the fairlead displacement. Numerical simulation and sensitivity analysis show that the wind turbine motion and its sensitivity to changes in the mooring system and COG are very large near resonant frequencies. The test results can be used to validate numerical simulation tools for FOWTs.

Short Wave Infrared Imaging for Auroral Physics and Aeronomy Studies

  • Trond S. Trondsen;John Meriwether;Craig Unick;Andrew Gerrard;Matthew Cooper;Devin Wyatt
    • Journal of Astronomy and Space Sciences
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    • v.41 no.2
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    • pp.121-138
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    • 2024
  • Advances in solar-terrestrial physics are generally linked to the development of innovative new sensor technologies, affording us ever better sensitivity, higher resolution, and broader spectral response. Recent advances in low-noise InGaAs sensor technology have enabled the realization of low-light-level scientific imaging within the short-wave infrared (SWIR) region of the electromagnetic spectrum. This paper describes a new and highly sensitive ultra-wide angle imager that offers an expansion of auroral and airglow imaging capabilities into the SWIR spectral range of 900-1,700 nm. The imager has already proven successful in large-area remote sensing of mesospheric temperatures and in providing intensity maps showing the propagation and dissipation of atmospheric gravity waves and ripples. The addition of an automated filter wheel expands the range of applications of an already versatile SWIR detector. Several potential applications are proposed herein, with an emphasis on auroral science. The combined data from this type of instrument and other existing instrumentation holds a strong potential to further enhance our understanding of the geospace environment.