• Title/Summary/Keyword: Effective force area

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Development of Online Model for Mean Effective Strain, Roll Force and Area Reduction in Bar Rolling with Three Rolls (콕스밀에서 평균변형율, 압하력, 단면감소율에 대한 수식모델개발)

  • Je S. H.;Hwang S. M.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2001.10a
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    • pp.162-165
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    • 2001
  • In industrial practice, caliber design in shape rolling depends on the designer's experience, which in general is obtained through costly trial-and error process. on-line model which is relations of mean effective strain, roll force and area reduction is derived from finite element process simultion in bar rolling with three rolls.

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Experimental Study for Effective Flow and Force Area of Discharge Valve System in a Linear Compressor (리니어 압축기 토출밸브계의 유효 유동면적 및 힘면적에 관한 실험적 연구)

  • Lee Byung-Chan;Lee Hyuk;Ahn Tae-Kil
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.7 s.184
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    • pp.122-129
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    • 2006
  • The linear compressor has lately attracted considerable attention because of its low power consumption and excellent efficiency. For an efficient design, it is necessary to develop an analytical model of the linear compressor. The effective flow and force areas are important parameters to describe the behavior of the linear compressor, which are used to determine the mass flow rates through the valving systems and the forces on the valves, respectively. It is not easy to estimate these parameters because shapes of the valve systems of the linear compressor are so different from those of tile conventional valve systems. In this paper, we suggest method to measure experimentally the effective discharge flow and force areas of the linear compressor and analyze valve characteristic to apply the experimental results to their theoretical model.

Fabrication of a novel dry adhesive structure with reduced effective stiffness (유효강성을 줄인 새로운 형상의 건식부착물 제작)

  • Cho, Young-Sam;Jung, Dae-Hwan;Han, Houk-Seop;Kim, Wan-Doo
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.421-425
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    • 2007
  • In the fabrication of dry adhesive structure, increasing contact-points or contact-area is the primary goal because the adhesive force grows in proportion to the contact-area. The simplest way to extend the contact surface is the fabrication by using soft materials. However, the column-array structure could confront the matting phenomenon which columns are stuck together. Therefore, we need a novel design to reduce the effective stiffness with adequate stiff materials like a gecko's setae. In this study, we propose a novel design for the dry adhesive structure. Moreover, we analyzed whether the adhesive structure conforms the rough surface sufficiently through finite element method adopted the non-bonding interaction as the body force. Also, we fabricated the novel structures via UV lithography and some techniques. In addition, we examined the adhesive force of the novel structures.

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Mean Cutting Force Prediction in Ball-End Milling of Slanted Surface Using Force Map (볼엔드밀 경사면 가공에서 절삭력 맵을 이용한 평균절삭력 예측)

  • 김규만;주종남
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.12
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    • pp.212-219
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    • 1998
  • During machining of dies and molds with sculptured surfaces. the cutter contact area changes continuously and results in cutting force variation. In order to implement cutting force prediction model into a CAM system, an effective and fast method is necessary. In this paper. a new method is proposed to predict mean cutting force. The cutter contact area in the spherical part of the cutter is obtained using Z-map, and expressed by the grids on the cutter plane orthogonal to the cutter axis. New empirical cutting parameters were defined to describe the cutting force in the spherical part of cutter. Before the mean cutting force calculation, the cutting force density in each grid is calculated and saved to force map on the cutter plane. The mean cutting force in an arbitrary cutter contact area can be easily calculated by summing up the cutting force density of the engaged grid of the force map. The proposed method was verifed through the slotting and slanted surface machining with various inclination angles. It was shown that the mean force can be calculated fast and effectively through the proposed method for any geometry including sculptured surfaces with cusp marks and holes.

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A Study on the Closing Force according to the Opening Angle of the Door in the Smoke Control System (제연구역 출입문 개방 각도에 따른 폐쇄력에 관한 연구)

  • Oh, Won-Sin;Joung, Suck-Hwan
    • Journal of the Korea Safety Management & Science
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    • v.23 no.4
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    • pp.43-48
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    • 2021
  • In this study, the experiment was conducted on a fire door(W × H = 0.98 m × 2.19 m) installed on the vestibule. The effective leakage area for each opening angles and closing forces derived from the impulse-momentum equation was compared and analyzed with the experimental results. As a result of the experiment, the major factors affecting the door closing forces were the pressure difference and the area of the door. The difference of door closing forces between measured and calculated values by the impulse-momentum equation showed a deviation of less than ±15% at the opening angles of 5°to 10°. At the door opening angle of 2.5°, the dynamic pressure was much higher than the measured static pressure, and this pressure difference is estimated to be air resistance acting to prevent the door from being completely closed.

Compressive Stress Distribution of High Tension Bolted Joints (고장력 볼트 이음부의 내부 압축응력 분포)

  • Kim, Sung Hoon;Lee, Seung Yong;Choi, Jun Hyeok;Chang, Dong Il
    • Journal of Korean Society of Steel Construction
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    • v.9 no.2 s.31
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    • pp.171-179
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    • 1997
  • The high-tension bolted joints are clamped by the axial force which approaches the yielding strength. The introduced axial force is transmitted to the connection members pass through washer. The transferred load in connections is balanced to the compressive stress of plates, axial force in bolts and the external loads. In this mechanism, the compressive stress and slip load we dominated by the effective stiffness of bolted joints and plates. In general the effective stiffness is specified to product to the effective area and elasticity modulus in connections. In this reason, the conic projection formular which is assumed that the axial force in bolts is distributed to the cone shape and that region is related to the elastic deformation mechanism in connections, was proposed. But it conclude what kind of formula is justified. Therefore in this paper, the fatigue tests are performed to the high tension bolted joints and inspected to the phase on the friction face. And using the FEM and numerical method, it is analyzed and approximated to the compressive stress distribution and its region. Moreover, it is estimated to the effective area and to the relation the friction area to the effective compressive distribution region.

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Acute Effects of Prolonged 15minnute Static Stretching on Foot Contact Area Surface and Foot Pressure Changed in Young Adults (15분간의 지속적인 스트레칭이 족저압과 족저면적 변화에 미치는 영향)

  • Kuk, Jung-Seok
    • Journal of Korean Physical Therapy Science
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    • v.18 no.4
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    • pp.59-64
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    • 2011
  • Purpose : The purpose of this study was to evaluate the effects of the stretching of the calf muscles on foot pressure and contact area in young adult. Participants stood on a wedge board that was sloped between 15~25 degree for 15min. After stretching participants stood quietly on force plate, result was recorded. Participants stood on a force plate for 1 min in eye closed condition, and them the foot pressure and area was recorded. The following variables were calculated off-line: anterior and posterior foot pressure and contact area, medial and lateral foot pressure and contact area. Results showed that anterior pressure change due to stretch, but mediolateral was not significant. This result suggested that stretching of the calf muscle has the effect of increasing anterior pressure by flexibility change on calf muscle, so this effects might be effective intervention for reduce of serious problem to neurologic patients in therapy session.

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Design and fabrication of 2MN hydraulic force standard machine (2MN 유압식 힘 표준기의 설계 및 제작)

  • Kang, D.I.;Song, H.K.;Lee, J.T.;Ahn, B.D.;Kim, C.Y.;Lee, J.Y.;Ahn, B.C.;Cheong, K.K.;Jeon, Y.H.
    • Journal of the Korean Society for Precision Engineering
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    • v.11 no.5
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    • pp.33-41
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    • 1994
  • For the establishment of large force standard and the accurate measurement of large force, 2MN hydraulic force standard machine which consists of loading frame, deadweight machine, two ram/cylinder systems and hydraulic control system was designed and fabricated. Measurement results of shapes for tow ram/cylinders reveal that the ratio of effective area is 200.094. The relative deviation of force stability for the machine is about .+-. 0.01% at 2MN and is less than .+-. 0.005% below 2MN. This machine may be widely used to calibrate the force measuring devices in industry and to test the force sensors.

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Analysis of Lorentz force of radial magnetic field type vacuum interrupter using finite element method (유한요소해석을 통한 횡자계 방식의 진공인터럽터 전극의 로렌츠 힘 분석)

  • KIM, Byoung-Chul;YOON, Jae-Hun;HOE, Jun;KANG, Seong-Hwa;LIM, Kee-Joe
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.1197-1198
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    • 2008
  • There have been few papers using finite element method(FEM) to analyze arc driving force for spiral type vacuum interrupter electrode up to date while there have been many papers dealing with AMF type electrode by means of FEM. AMF analysis is very important in AMF type electrode because it has proportional relation with effective area which means the area of magnetic flux density above critical magnetic flux density to diffuse arc. In the same manner, arc driving force is an important factor to drive arc by Lorentz force. In this paper two models were calculated and compared by using commercial FEM software Maxwell 3D.

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Analysis of Geometric Stability in Robot Force Control (로보트를 이용한 힘제어에서의 기하학적 안정성에 관한 해석)

  • 이병주
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.9
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    • pp.2284-2296
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    • 1994
  • Force control of robotic mechanisms continues to be a challenging area. Previous implementation have seldom produced satisfactory results, and researchers in the past have experienced significant instability problems associated with their force controllers. In this study, a new stability factor in force control will be pointed out. When a manipulator is constrained to an environment(force-controlled), geometric instability due to the relationship between the manipulator configuration and the force-controlled direction is shown to be a significant factor in overall system stability. This exploratory study points out a rather intuitive, geometrically based stability factor in terms of an effective system stiffness and analyzes the phenomenon both analytically and graphically. Also, a stiffness control algorithm using the kinematic redundancy of a kinematically redundant manipulator is proposed to improve the overall stability in force control.