• Title/Summary/Keyword: Maximum and minimum pressure

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A Study on Dust Explosion Characteristics of Hydroxypropyl Methyl Cellulose (Hydroxypropyl Methyl Cellulose의 분진 폭발특성에 관한 연구)

  • 임우섭;목연수
    • Journal of the Korean Society of Safety
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    • v.15 no.4
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    • pp.95-100
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    • 2000
  • This study was performed in Hartmann type dust explosion apparatus in order to research the dust explosion characteristics of hydroxypropyl methyl cellulose(HPMC): minimum explosive limit, minimum ignition energy, limiting oxygen concentration, maximum explosion pressure, rate of pressure rise, etc. The samples of HPMC dust were distributed into 120-140 mesh, 170-230 mesh and 325 under, and the gap distance of the discharge electrode was setted up at 5mm. The experimental results were obtained as follows: (1) The minimum explosive limit for HPMC dust was founded at 180g/㎥. the minimum ignition energy at 9.8mJ and the limiting oxygen concentration at 12%. (2) The maximum explosion pressure of HPMC dust was $8.1kg/cm^2\;{\cdot}\;$abs at the concentration of $500g/m^3$ and the maximum rate of pressure rise was 203.98 bar/sec at the concentration of $480g/m^3$ for 325 under.

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A Numerical Analysis of the Elastohydrodynamic Lubrication of Connecting Rod Bearings (커넥팅 로드 베어링의 EHL에 관한 수치해석)

  • 김병직;김경웅
    • Tribology and Lubricants
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    • v.12 no.3
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    • pp.63-71
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    • 1996
  • The connecting rod bearing, which is subjected to periodical dynamic loading, is an impoRant component of the reciprocating engine. In the operation of this bearing, significant parameters are the oil film thickness and the film pressure. Peak film pressures of 20-30 MPa are not uncommon. So the elastic deformation of the bearing housing can have a significant effect on the bearing performance. In this study, a numerical analysis of connecting rod bearing is investigated. Elastic deformation of the bearing housing is considered in the analysis. Separate hydrodynamic and structural analysis are coupled through a direct iterative process. It is shown that as the result of the elastic deformation of the bearing housing, the eccentricity ratio is increased, and the minimum value of the minimum film thickness and the maximum value of the maximum film pressure are decreased. The variations of rotational speed and cylinder pressure affect the minimum film thickness and the maximum film pressure variations of the connecting rod bearing.

Analysis of Bale Surface Pressure According to Stretch Film Layer Changes on Round Bale Wrapping

  • Hong, Sungha;Kang, Daein;Kim, Daeyeon;Lee, Sangsik
    • Journal of Biosystems Engineering
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    • v.42 no.3
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    • pp.136-146
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    • 2017
  • Purpose: This paper presents an appropriate wrapping method by analyzing the pressure distribution applied to a bale surface, along with the change in pressure according to an increase in the number of film layers in rice straw bales, which account for 74% of the total bulky feed supply in Korea. Methods: A model with the shape of an actual bale was fabricated to analyze the distribution of surface pressure in bale wrapping, and the pressure was measured. Experiments were conducted to analyze the pressure using eight different layer numbers (2, 4, 6, 8 10, 12, 14, and 16 layers) at five wrapping speeds (27, 29, 31, 33, and 35 rpm). Results: The maximum pressure applied to a circular bale by the film occurred at the center of the end of the bale, whereas the minimum pressure occurred at the center of the bale side. An extreme value ratio between the minimum and maximum pressures was distributed as 8.5-56.6%, which was improved with an increase in rotation speed. The an uneven pressure distribution occurred because the number of film overlaps was 8.24-times greater at the center of the bale's end than at the center of the ba le side. At a level 5 rotation speed, the minimum pressure was $P_{LV5-M1}=0.0625{\sigma}^2+36.173{\sigma}-36.753$ ($R^2=0.9845$) at $M_1$, and the maximum pressure was $P_{LV5-M6}=5.5552{\sigma}^2+41.05{\sigma}-39.071$ at $M_2$, revealing a correlation of $R^2=0.9983$. Conclusions: To replace four layers with six layers, 2-4 layers were added only to the side of the bale, and the minimum pressure at $M_1$ was then improved from that at four layers to that at six layers, and the amount of film consumed for 4-6 layers was reduced by 84.6%.

An Experimental Study on the Pressure and Temperature Distribution in a Plain Journal Bearing (저어널베어링의 압력 및 온도분포에 관한 실험적 연구)

  • 신영재;김경웅
    • Tribology and Lubricants
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    • v.4 no.1
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    • pp.69-73
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    • 1988
  • The effects of journal speed and bearing load on pressure distribution and the temperature distribution of bearing surface are investigated experimentally. The journal bearing which has 219.94mm diameter, length-to-diameter ratio of L/D=0.8 and clearance ratio of 0.004 is used. Journal has a built-in pressure transducer for the measurement of pressure distribution in the mid plane of bearing. Bearing surface temperatures are measured at 60 points. The bearing load is varied from 300 N to 5900 N and journal speed from 300 rpm to 2500 rpm. As the load is increased under constant speed, the location of maximum pressure moves to the site of minimum film thickness, and maximum pressure and absolute value of minimum pressure are increased. The temperature distribution in vicinity of oil inlet shows that heated lubricant's carry-over exists around the oil inlet.

A Study of Surge Pressure Absorption by Water Hammer Arrester in Water Supply Piping System (워터 햄머 흡수기의 압력흡수 효과에 관한 연구)

  • 이용화;유지오
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.12
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    • pp.1066-1072
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    • 2000
  • This study is to investigate the pressure wave characteristics and the absorption of maximum and minimum pressure generated by instantaneous valve closure at the end of the straightening copper piping system with and without a water hammer arrester. Experiments were conducted under the following conditions : initial pressure 1~5 bar, flow velocity 0.6~3.0 m/s, water temperature $20^{\circ}C$ and air volume of water hammer arrester $80~180^cm^3$. Experimental results show that the optimum air volume of water hammer arrester is 110㎤.

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Development of Blood Pressure Measurement Method Using ANFIS (ANFIS를 이용한 전자 혈압 측정 알고리즘 개발)

  • Chun Myung-Geun;Kwon Seok-Young;Lee Dae-Jong
    • Journal of the Korean Institute of Intelligent Systems
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    • v.16 no.4
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    • pp.493-498
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    • 2006
  • In this paper, we propose a blood pressure measurement method using ANFIS. Usually, the maximum and minimum blood pressures are calculated by Maximum Amplitude Algorithm(MAA) method. However, the MAA method has some drawbacks to measure exact blood pressure since it uses a fixed ratio to set the measuring points for everyone without considering individual's special conditions. To solve this problem, the pressures measured by the MMA are trained by ANFIS having self-learning ability. From various experiments, we confirm that the proposed method shows better performance than conventional method.

The Effect of Air Chamber Placed in Water Supply Piping System (급수배관계에서 에어 챔버의 설치효과에 관한 연구)

  • 이용화;최국광
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.12
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    • pp.1047-1055
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    • 2002
  • The present study is to investigate the pressure wave characteristics and the absorption of the maximum and minimum pressure generated by instantaneous valve closure and opening at the end of the straightening copper Piping system with and without an air chamber. Also, life of air chamber is investigated. Experiments were conducted under the following conditions: initial pressure of 1~5 bar, flow velocity of 0.5~3.0 m/s, water temperature of$20^{\circ}C$ and air chamber volume of 45.1~449.5$cm^3$ The results of the study can be used in sizing air chamber and selecting the water hammer absorbtion apparatus.

Risk Assessment of Explosion of Mixed Dust Generated in Semiconductor Manufacturing (반도체 공정에서 발생하는 혼합분진의 폭발 위험성평가)

  • Park, Chang-Sup;Kim, Chan-O
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.3
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    • pp.474-478
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    • 2018
  • The use of metals such as aluminum and titanium and the related industrial facilities have been continuously increasing to meet the requirements of the improvement of high-tech products due to the development of industry, and explosion of metal dust. Semiconductor process Metal dust is essential, but research is insufficient. The purpose of this study is to identify risk by analyzing the quantitative risk such as maximum explosion pressure and minimum explosion concentration applied international test standard in order to select the semiconductor process facilities handling dust and to predict possible risk of accidents.

Maximum axial load level and minimum confinement for limited ductility design of high-strength concrete columns

  • Lam, J.Y.K.;Ho, J.C.M.;Kwan, A.K.H.
    • Computers and Concrete
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    • v.6 no.5
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    • pp.357-376
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    • 2009
  • In the design of concrete columns, it is important to provide some nominal flexural ductility even for structures not subjected to earthquake attack. Currently, the nominal flexural ductility is provided by imposing empirical deemed-to-satisfy rules, which limit the minimum size and maximum spacing of the confining reinforcement. However, these existing empirical rules have the major shortcoming that the actual level of flexural ductility provided is not consistent, being generally lower at higher concrete strength or higher axial load level. Hence, for high-strength concrete columns subjected to high axial loads, these existing rules are unsafe. Herein, the combined effects of concrete strength, axial load level, confining pressure and longitudinal steel ratio on the flexural ductility are evaluated using nonlinear moment-curvature analysis. Based on the numerical results, a new design method that provides a consistent level of nominal flexural ductility by imposing an upper limit to the axial load level or a lower limit to the confining pressure is developed. Lastly, two formulas and one design chart for direct evaluation of the maximum axial load level and minimum confining pressure are produced.

Numerical Analysis on the Oil Film Behavior of Engine Main Bearing Considering Dilution of Diesel Fuel (경유 혼입을 고려한 엔진 메인 베어링의 유막거동에 관한 수치적 연구)

  • Kim, Han-Goo
    • Tribology and Lubricants
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    • v.26 no.4
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    • pp.240-245
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    • 2010
  • This paper describes the influence on engine main bearing behavior of the oil film when the fuel is diluted on a diesel engine equipped with DPF system. Oil film pressure and the thickness is calculated in accordance to the fuel dilution. The calculation is based on the numerical analysis of the engine main bearing. As a result, the engine oil viscosity decreased as the fuel dilution increased. This led the increment of the maximum oil thickness pressure. Verification of the minimum oil film thickness settlement by the engine gas pressure and the fuel dilution was confirmed. Destruction possibility of the engine main bearing was foreseen when the engine speed was 2000 rpm with the fuel dilution 15% and the 5W40 engine oil.