• Title/Summary/Keyword: Pressure

Search Result 44,763, Processing Time 0.158 seconds

Pressure Monitoring System in Gastro-Intestinal Track (소화기관내의 압력 모니터링 시스템)

  • 김용인;박석호;김병규;박종오
    • Journal of Institute of Control, Robotics and Systems
    • /
    • v.10 no.11
    • /
    • pp.1089-1094
    • /
    • 2004
  • Diseases in the gastro-intestinal track are on an increasing trend. In order to diagnose a patient, the various signals of the digestive organ, such as temperature, pH, and pressure, can offer the helpful information. Among the above mentioned signals, we choose the pressure variation as a monitoring signal. The variation of a pressure signal of the gastro-intestinal track can offer the information of a digestive trouble or some clues of the diseases. In this paper, a pressure monitoring system for the digestive organs of a living pig is presented. This system concept is to transmit the measured biomedical signals from a transmitter in a living pig to wireless receiver that is positioned out of body. The integrated solution includes the following parts: (1) the swallow type pressure capsule, (2) the receiving set consisting of a receiver, decoder box, and PC. The merit of the proposed system if that the monitoring system can supply the precise and repeatable pressure in the gastro-intestinal track. In addition, the design of low power consumption enables it to keep sending reliable signals while the pressure capsule is working in the digestive organ. The subject of the study for the pressure monitoring system is in-vivo experiments for a living pig. We achieved the pressure tracings in digestive organs and verified the validity of system after several in-vivo tests using pressure monitoring system. As a result, we found each organ has its own characterized pressure fluctuation.

Parametric Study on the Pressure Continuity Residual for the Stabilization of Pressure in Incompressible Materials (비압축성 물체의 압력해 안정화를 위한 압력연속여분치의 매개변수 연구)

  • 이상호;김상효
    • Computational Structural Engineering
    • /
    • v.8 no.4
    • /
    • pp.189-198
    • /
    • 1995
  • The conventional finite element formulations for incompressible materials show pressure oscillations or pressure modes in four-node quadrilateral elements of commonly used displacement and pressure interpolations. The criterion for the stability in the pressure solution is the so-called Babugka-Brezzi stability condition, and the above elements do not satisfy this condition. In this study, a pressure continuity residual based on the pressure discontinuity at element interfaces is used to study the stabilization of pressure solutions in bilinear displacement-constant pressure four-node quadrilateral elements. This pressure residual is implemented in Q1P0 element derived from the conventional incompressible elasticity. The pressure solutions can be stable with the pressure residual though they exhibit sensitivity to the stabilization parameters. Parametric study for the solution stabilization is also discussed.

  • PDF

A Study on a High-Temperature/High-Pressure Washing System in which High-Temperature Water is Generated in a Low-Pressure Boiler and High-Pressure Water is Generated Thereafter in a Compressor (저압보일러에서 고온의 온수 생성 후 압축기에서 고압수를 생성하는 고온·고압 세척시스템에 관한 연구)

  • Cho, Dong-Hyun
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.18 no.1
    • /
    • pp.94-100
    • /
    • 2019
  • This study was conducted on a high-temperature/high-pressure washer in which low-pressure cold water in a boiler is heated to a temperature range of $70{\sim}80^{\circ}C$ by supplying diesel combustion heat. The high-temperature water is sent to a compressor to increase its pressure to 200 bar, thereby making high-temperature/high-pressure water, which is sprayed through a spray nozzle. In the results of this study, the spray temperature of the high-pressure washing was shown to be the highest when the ratio between the actual amount of combustible air and the theoretical amount of air was 1:1 and the energy consumption rate of the low-pressure boiler type high-pressure washer was shown to be much lower than that of the high-pressure boiler type high-pressure washer.

Heat Transfer Characteristics of an Internally-Heated Annulus Cooled with R-134a Near the Critical Pressure

  • Hong, Sung-Deok;Chun, Se-Young;Kim, Se-Yun;Baek, Won-Pil
    • Nuclear Engineering and Technology
    • /
    • v.36 no.5
    • /
    • pp.403-414
    • /
    • 2004
  • An experimental study of heat transfer characteristics near the critical pressure has been performed with an internally-heated vertical annular channel cooled by R-134a fluid. Two series of tests have been completed: (a) steady-state critical heat flux (CHF) tests, and (b) heat transfer tests for pressure reduction transients through the critical pressure. In the present experimental range, the steady-state CHF decreases with increase of the system pressure for fixed inlet mass flux and subcooling. The CHF falls sharply at about 3.8 MPa and shows a trend towards converging to zero as the pressure approaches the critical point of 4.059 MPa. The CHF phenomenon near the critical pressure does not lead to an abrupt temperature rise of the heated wall, because the CHF occurs at remarkably low power levels. In the pressure reduction transients, as soon as the pressure passes below the critical pressure from the supercritical pressure, the wall temperatures rise rapidly up to very high values due to the departure from nucleate boiling. The wall temperature reaches a maximum at the saturation point of the outlet temperature, and then tends to decrease gradually.

A Study on the Pulsation Pressure Reduction for the Hydraulic System of Medium-Large Excavator (중대형 굴삭기 유압시스템의 압력 맥동 저감 연구)

  • Kim, Young-Hyun;Joo, Won-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • /
    • pp.421-426
    • /
    • 2010
  • With hydraulic noise test facility, a variety of tests were performed to investigate the pulsation pressure generation mechanism and its transmission characteristics and to derive the noise control methodology. Many experiments were carried out by changing average pressure, flow rate, pump speed, hose length and MCV spool condition. From the test results, the correlations between pulsation pressure and other design parameters, such as static pressure, flow rate and MCV spool opening area and length of hose, were found out. And also each contribution factors were evaluated from the regression analysis. By changing hose length, the pulsation pressure resonance phenomenon was investigated. In order to find out the pulsation pressure reduction measures pulsation pressure analysis, such as pulsation pressure of hydraulic pump itself and pulsation pressure of hydraulic system, by using AMESim were studied. In addition hydraulic silencer was developed based on the Helmholtz resonator. And its performance was evaluated by installing the silencer at the excavator.

  • PDF

Qualitative Analysis of Pressure Intensity and Center of Pressure Trajectory According to Shoe Type

  • Yi, Kyung-Ock
    • Korean Journal of Sport Biomechanics
    • /
    • v.22 no.3
    • /
    • pp.261-268
    • /
    • 2012
  • The purpose of this study was to qualitatively analyze pressure intensity and the center of pressure(COP) trajectory according to shoe type. Subjects were ten first-year female university students. The EMED-AT 25/D(Novel, Germany) was used to measure pressure intensity and COP trajectory. The COP Excursion Index(CPEI) was used for within subject test design. Independent variables were bare feet and six types of shoes. Dependent variables were center of pressure trajectory and pressure intensity. Barefeet and five toed shoes had a similar pressure intensity and COP trajectory. COP trajectory for all other shoe types showed a medial wobble at the heel. Pressure intensity for all other shoe types was related to the structure of the shoes. In conclusion, different shoe types can not only affect gait, but they can also influence foot deformities, pain, and dysfunction.

A Study on the Optimal Pressure Curve for the Sheet Hydroforming (판재 액압성형 공정에서의 최적압력곡선에 관한 연구)

  • 심현보;양희태;서의권;양동열
    • Transactions of Materials Processing
    • /
    • v.11 no.3
    • /
    • pp.246-254
    • /
    • 2002
  • A simple method to derive an optimal pressure curve, characterized by initial pressure, final pressure and pressure path, has been proposed. The initial pressure has been determined from the condition to prevent recoiling phenomenon in the early stage, while the final pressure is from the FE analysis and pressure path is from the punch penetration volume. In order to realize the pressure curve, an open loop control system based on a proportional relief valve has been developed for the renovated CNC hydroforming press. Through the comparison of experiment and analysis, the predicted pressure curve has been verified optimal curve since no defect has been observed.

A Micro Passive Gas Pressure Regulator using Pressure Balance Mechanism (압력평형메커니즘을 이용한 초소형 수동형 기체 압력조정기)

  • Lee, Ki-Jung;Yang, Sang-Sik
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.59 no.1
    • /
    • pp.138-143
    • /
    • 2010
  • This paper presents the analysis, the fabrication and the test results of a micro passive gas pressure regulator to keep the outlet pressure costant even for a widely-varying inlet pressure. This device is to regulate the outlet pressure according to the applied reference pressure based on the pressure balancing mechanism of the structure including a membrane and a valve. This regulator consists of four layers; a bulk-micromachined silicon substrate, a sandblasted glass substrate, a PDMS valve seat layer and a glass valve layer. The device size is $10\times13\times1.7 mm3$. The device was fabricated by micromachining. The characteristic of the device was analyzed and tested. The characteristic of the fabricated pressure regulator is similar to that obtained from the analysis. The pressure regulator of this paper is feasible for portable systems and miniature drug delivery systems.

Correlation between the subjective comfort and elastic body pressure distribution on a bicycle saddel (자전거 안장의 연체압 분포와 주관적 안락도의 상관성에 관한 연구)

  • 최정윤;박경수
    • Proceedings of the ESK Conference
    • /
    • /
    • pp.145-145
    • /
    • 1993
  • In bicycle design, saddle is the major part which effects the subjective comfort of rider. This study examines the correlation between the subjective comfort and elastic body pressure. The elastic body pressure measuring instrument for free-form surface such as saddle is developed by force sensor register, A/D converter and computer. The subjective comfort is measured quantit- atively by 11-point scale method and the elastic body pressure distribution is obtained through 3 different saddles at 4 postures. The pressure distribution is presented by computerized equi- pressure contour. While mean pressure, standard deviation of pressure, maximum pressure are inversely proportional to subjective comfort, the modified saddle-bearing weight which is the surface integral of pressure is directly proportional. Consequently, standard deviation of pressure is most important characteristic which affects variation of subjective comfort.

  • PDF

Effect of Bundle Junction Face and Misalignment on the Pressure Drops Across a Randomly Loaded and Aligned 12 Bundles in Candu Fuel Channel

  • H. C. Suk;K. S. Sim;C. H. Chung;Lee, Y. O.
    • Nuclear Engineering and Technology
    • /
    • v.28 no.3
    • /
    • pp.280-289
    • /
    • 1996
  • The pressure drop of twelve fuel bundle string in the CANDU-6 fuel channel is equal to the sum of the eleven junction pressure losses, the bundle string entrance and exit pressure losses, the skin friction pressure loss, and other appendage pressure losses, where the junction loss is dependent on the bundle end faces and angular alignments of the junctions. The results of the single junction pressure drop tests in a short rig show that the most probable pressure drop of the eleven junctions was analytically equal to the eleven times of average pressure drop of all the possible single junction pressure drops, and also that the largest and smallest junction pressure drops across the eleven junctions probably occurred only with BA and BB type junctions, respectively, where A and B denote the bundle end sides with an end-plates on which a company monogram is stamped and unstamped, respectively.

  • PDF