• Title/Summary/Keyword: Relief displacement

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Case Report : Treatment of Disc Displacement without Reduction Patient Using ARS (전방재위치 교합장치를 이용한 비정복성 관절원판변위 환자의 치험례)

  • 진상배;홍정표
    • Journal of Oral Medicine and Pain
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    • v.23 no.3
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    • pp.277-280
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    • 1998
  • The treatment of anterior disc displacement without reduction patients needs speicific treatment methods different from other Craniomandibular Disorders. Those are manual manipulation, anterior repositioning splint; ARS and step-back. It is well known that the use of Anterior Repositioning Splint is effective on relief of TMJ symptom. But the side effect of long- term ARS wearing, which is irreversible posterior open bite induction, has made many clinicians avoid ARS treatment. This report introduces a clinical case recently proven part- time wearing ARS method for treatment of Disc Displacement without reduction patient' that can reduce side effects with good efficacy. But now clinical statistical studies and basical histophysiological studies are more needed.

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Comparison of Cushion Performance on Parameter Changes in High Speed Pneumatic Cylinder Driving System (공기압 실린더 고속 구동시스템에서 파라미터 변화에 따른 쿠션성능 비교)

  • Kim, Do Tae;Jang, Zhong Jie
    • Journal of Drive and Control
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    • v.12 no.4
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    • pp.54-59
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    • 2015
  • Due to the tendency to use high speed pneumatic cylinders to improve productivity, cushioning devices are adopted to decelerate the piston motion of pneumatic cylinders to reduce noise, vibration, and impact. This paper presents a comparison of the cushion characteristics of a high speed pneumatic cylinder with a relief valve type cushioning device. The system parameters selected are the damping coefficient, Coulomb friction, heat transfer coefficient, and cracking pressure of the relief valve in the air cushioning device. The integral of the time multiplied square error (ITSE) is used to quantitative measure the cushioning performance to assess the effect of varying these. The cushioning performance achieved good results when the ITSE is a minimum value. In a comparison of the piston displacement and velocity with the variations in system parameters, the heat transfer coefficients are not as significantly affected as the other. Also, the cracking pressure of the relief valve is mainly affected by the pressure and temperature in the cushion chamber.

A Numerical Study on the Flow Characteristics through an Industrial Safety Relief Valve (산업용 안전 릴리프밸브 유동특성에 관한 수치연구)

  • Kang, Sang-Mo;Lee, Bong-Hee
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.5
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    • pp.696-704
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    • 2009
  • In this paper, the flow characteristics through an industrial safety relief valve used to protect the crankcase room in a large-sized marine engine have been numerically investigated using the moving-mesh strategy. With the room pressure higher than the cracking one, the spring-loaded disc becomes open and then the air in the room blows off into the atmosphere, resulting in the reduction of the room pressure and then the shutoff of the disc. Numerical simulations are performed on the compressible air flow through the relief valve (${\phi}160mm$) with the initial room pressure (0.11 bar or 0.12bar) higher than the cracking one (0.1 bar). The numerical method has been validated by comparing the results with the empirical ones. Results show that the disc motion and flow characteristics can be successfully simulated using the moving-mesh strategy and depend strongly on the spring stiffness and the flow passage shape. With increasing spring stiffness, the maximum disc displacement decreases and thus the total disc-opening time also decreases. In addition, the flow passage shape makes a significant effect on the velocity and direction of the flow.

Effect of arthrocentesis on the clinical outcome of various treatment methods for temporomandibular joint disorders

  • Kim, Chang-Woo;Lee, Sung-Jae;Kim, Euy-Hyun;Lee, Dong-Keon;Kang, Mong-Hun;Song, In-Seok;Jun, Sang-Ho
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.41
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    • pp.44.1-44.7
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    • 2019
  • Background: We evaluated the improvement of pain and the increase in mouth opening after temporomandibular joint arthrocentesis and the possible association with various factors such as previous splint treatment, medication, and diagnosis. Results: We studied 57 temporomandibular joint disorder patients who underwent arthrocentesis at Korea University Anam Hospital. These patients (24 males and 33 females, aged between 15 and 76 years) underwent arthrocentesis that was performed by one surgeon. The degree of mouth opening (assessed using the maximum mouth opening: MMO) and pain (assessed using the visual analog scale: VAS) were assessed pre- and post-arthrocentesis. The study also investigated whether treatment modalities other than arthrocentesis (medication and appliance therapy) were performed. Statistical analysis revealed that there was a significant difference in mouth opening and pain after temporomandibular joint arthrocentesis. Preoperative appliance therapy affected the results of arthrocentesis, but it was not statistically significant. With regard to pain relief, preoperative diagnosis did not show a significant difference. However, with regard to maximum mouth opening, patients with disc displacement without reduction with limited mouth opening (closed lock) showed the highest recovery (11.13 mm). Conclusion: The average of MMO increase after arthrocentesis was 9.10 mm, and patients with disc displacement without reduction with locking (closed lock) showed most recovery in maximum mouth opening and it was statistically significant. The average pain relief of patients after arthrocentesis was 3.03 in the VAS scale, and patients using anterior repositioning splint (ARS) preoperatively showed the most pain relief.

SUBSIDENCE AT DUK-PO AREA REVEALED BY DINSAR AND INTERFEROGRAM STACKING

  • Hong, Sang-Hoon;Kim, Sang-Wan;Won, Joong-Sun
    • Proceedings of the KSRS Conference
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    • 2002.10a
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    • pp.308-311
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    • 2002
  • Radar interferometric phase is sensitive to both ground topography and coherent surface displacement. The basic tactics of differential interferometric synthetic aperture radar (DInSAR) technique are to separate the two effects. Applications of DInSAR to Duk-Po area in Busan were studied. In the study area, an abrupt subsidence, possibly caused by sub-way construction, was observed by JERS-1 SAR interferometry. Differential interferograms were generated using twenty-three JERS-1 SAR data acquired between April 24, 1992, and August 7, 1998. Because the area is relatively flat with little topographic relief the topographic effects were not removed. A phase filtering and interferogram techniques were applied to increase fringe clarity as well as to decrease decorrelation error. The stacking improves the quality of interferograms especially when the displacement is discontinuous. The interferograms clearly show the evidence of subsidence along Duk-Po subway railroad. These results demonstrate that the interferogram stacking technique can improve the detectability of radar interferometry to an abrupt displacement and DInSAR is useful to geological engineering applications.

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Dynamic behavior of submerged floating tunnels at the shore connection considering the use of flexible joints

  • Seok-Jun Kang;Minhyeong Lee;Jun-Beom An;Dong-Hyuk Lee;Gye-Chun Cho
    • Geomechanics and Engineering
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    • v.33 no.1
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    • pp.101-112
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    • 2023
  • When a submerged floating tunnel is connected to the ground, there is a risk of stress concentration at the shore connection owing to the displacement imbalance caused by low confinement pressures in water and high confinement pressures in the ground. Here, the effects of the boundary condition and stiffness of the joints installed at the shore connection on the behaviors of a submerged floating tunnel and its shore connection were analyzed using a numerical method. The analysis results obtained with fixed and ground boundaries were similar due to the high stiffness of the ground boundary. However, the stability of the shore connection was found to be improved with the ground boundary as a small displacement was allowed at the boundary. The effect of the joint stiffness was evaluated by investigating the dynamic behavior of the submerged floating tunnel, the magnitude of the load acting on the bored tunnel, and the stress distribution at the shore connection. A lower joint stiffness was found to correspond to more effective relief of the stress concentration at the shore connection. However, it was confirmed that joints with low stiffness also increase the submerged floating tunnel displacement and decrease the frequency of the dynamic behavior, causing a risk of increased resonance when wave loads with low frequency are applied. Therefore, it is necessary to derive the optimal joint stiffness that can achieve both stress concentration relief and resonance prevention during the design of shore connections to secure their dynamic stability.

A study on matching correlation analysis of multi-scale satellite images data for change detection (변화추출을 위한 다중영상자료의 정합상관도 분석을 위한 연구)

  • 이성순;윤희천;강준묵
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • 2004.04a
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    • pp.221-226
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    • 2004
  • For comparing more than two images, the precise geometric corrections should be preceded because it necessary to eliminate systematic errors due to basic sensor information difference and non-systematic errors due to topographical undulations. In this study, we did sensor modeling using satellite sensor information to make a basic map of change detection for artificial topography. We eliminated the systematic errors which can be occurred in photographing conditions using GCP and DEM data. The Kompsat EOC images relief could be reduced by precise rectification method. Classifying images which was used for change detections by city and forest zone, the accuracy of the matching results are increased by 10% and the positioning accuracies also increased.

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A Study on the Mechanical Behavior of Preflex Beam under Different Preflexion Loading Conditions (재하방법에 따른 프리플렉스빔의 역학적 거동에 관한 연구)

  • 방한서;주성민;김규훈;안해영
    • Journal of Welding and Joining
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    • v.22 no.2
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    • pp.33-37
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    • 2004
  • Since the preflex beam is fabricated by welding, the pre-compressive stresses that should occur over the concrete pier are diminished by the welding residual stresses. For this reason distribution of welding residual stresses must be analyzed accurately and welding residual stresses should be relieved during the fabrication. In this study strain history, displacement of beam and re-distributed welding residual stresses by different loading conditions are measured and compared to choose more appropriate preflex condition.

Active Earth Pressure Acting on the Cylindrical Retaining Wall of a Shaft (원형수직구의 흙막이 벽체에 작용하는 주동토압)

  • Chun, Byungsik;Shin, Youngwan
    • Journal of the Korean GEO-environmental Society
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    • v.7 no.4
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    • pp.15-24
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    • 2006
  • It is well known that earth pressure on the cylindrical open caisson and cylindrical retaining wall of a shaft is less than that at-rest and in plane strain condition because of the horizontal and vertical arching effects due to wall displacement and stress relief. In order to examine the earth pressure distribution of a cylindrical wall, model tests were performed in dry sand for the care of constant wall displacement with depth. Model test apparatus which can control wall displacement, wall friction, and wall shape ratio was developed. The effects of various factors that influence earth pressure acting on the cylindrical retaining wall of a shaft were investigated.

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A Study on the Meter-Out and Meter-In Speed Control Characteristics in Pneumatic Cushion Cylinders (공기압 쿠션 실린더의 미터아웃/미터인 속도제어 특성에 관한 연구)

  • Kim, Do-Tae
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.22 no.1
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    • pp.1-7
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    • 2013
  • Pneumatic cylinders are widely used to actuators in automatic equipments because they are relatively inexpensive, simple to install and maintain, offer robust design and operation, are available in a wide range of standard sizes and design alternatives. This paper presents a comparative study among the dynamic characteristics of meter-out and meter-in speed control of pneumatic cushion cylinders with a relief valve type cushion mechanism. Because of the nonlinear differential equations and a requirement for simultaneous iterative solution in a mathematical model of a double acting pneumatic cushion cylinder, a computer simulation is carried out to investigate pressure, temperature, mass flow rate in cushion chamber and displacement and velocity time histories of piston under various operating conditions. It is found that the piston velocity and pressure response in meter-in speed control are more oscillatory than with meter-out those when pneumatic cushion cylinders are driven at a high-speed. In meter-out speed control, the effective area of the flow control valve is larger than that of meter-in, and the supply pressure has to be much higher than the pressure required to move the load because it has also to overcome the back pressure in cushion chamber.