• Title/Summary/Keyword: Pressure Distribution

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A Study on the Characteristics of Pressure Distribution for Heat Exchanger Types of Domestic Gas Boiler (가정용 가스보일러 열교환기 유형에 따른 압력분포특성에 관한 연구)

  • 최경석;오율권;차경옥
    • Journal of the Korean Society of Safety
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    • v.16 no.4
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    • pp.22-28
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    • 2001
  • Heat transfer and pressure distribution for heat exchanger type of domestic gas boiler are different from shape, pitch, thickness of fin and array of pipe respectively. In order to measure the pressure distribution across the heat exchanger, a suction type wind tunnel was constructed and velocity distribution was measured for pilot tube(4 point) of rack type. The experiments were performed for 5 different air flow mass, rpm=3,6,9,12,15 and transverse axis of heat exchanger(x-length) is 5cm respectively. Results showed that above 9.5m/s, pressure distribution dispersion for wet type of heat exchanger is on the increase and above 5.5m/s, pressure distribution dispersion for dry type of heat exchanger is on the increase. Also, pressure distribution dispersion by comparing two different types heat exchanger, dry type of heat exchanger showed a higher augmentation than wet type of heat exchanger.

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The Effect of Pressure Distribution on the both Foots With Gluteus Medius Muscle Intensive Strengthening Exercise in 4Weeks. (4주간의 중간볼기근 중점 강화운동이 양쪽 발의 압력 분포에 미치는 영향)

  • Park, Sam-Ho;Park, Jong-Hang;Kim, Yoon-hwan
    • The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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    • v.24 no.1
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    • pp.67-75
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    • 2018
  • Background: The purpose of this study was to investigate the effect of pressure distribution on the both foots with gluteus medius muscle intensive strengthening exercise in 4week. Methods: The purpose of this study was to investigate the effect of gluteus medius muscles strengthening exercise on the pressure distribution of the foot in 20 healthy adults. Four gluteus medius muscles strengthening exercise programs were conducted three times a week for four weeks. The pressure distribution changed of the right and left foot parts of the experimental group and the control group were measured and analyzed. Results: There was a significant difference in F1, F2, M1, M2, and H1 among the pressure distribution of the right foot of the experimental group (p<.05). There was a significant difference in F1, M1, M2, H1 and H2 among the pressure distributions of the left foot of the experimental group (p<.05). There was a significant difference in H1 among the pressure distribution of the right foot of the control group (p<.05). There was no significant difference in the pressure distribution of the left foot region of the control group (p>.05). There was a significant difference in H1 among the pressure distribution of the right foot between the group (p<.05). There was a significant difference in M2, H1 among the pressure distribution of the left foot between the group (p<.05). Conclusions: In the healthy adults, it was confirmed that the application of the gluteus medius muscles strengthening exercise had an effect on the weight shift during the walking due to the overall foot balance and the pressure distribution change of the foot part.

A Basic Study for the Variation of Nodal Demands According to the Low Pressure in Water Distribution Systems (배수관망내 수압부족시 절점수요량의 변화에 대한 기초적 고찰)

  • Hyun, In-Hwan;Lee, Sang-Mok;Kim, Young-Hwan;Ahn, Yong-Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.16 no.6
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    • pp.726-732
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    • 2002
  • Pressure drop could happen in the water distribution systems due to pipe breaks or maintenance. The pressure drop causes the water service shutdown and nodal water demands should be reduced in some areas. The conventional analysis method of water distribution systems can not consider the change of nodal water demands caused by these pressure drops. This study is to investigate the variation of nodal water demands according to the nodal water pressure and its effect on the analysis of water distribution systems. For these purpose, one real water service district was selected as a study area. As a result, nodal water demand patterns according to the water pressure could be suggested. Also, we could confirm that the suggested new analysis method for the water distribution systems which considering water pressure drops could be more reliable than the conventional method.

The Correlation of Foot Pressure with Spinal Alignment in Static Standing (정적 기립 자세에서 족저압 분포와 척추 정렬과의 상관관계 연구)

  • Lim, Jae-Heon;Ko, Hyo-Eun
    • PNF and Movement
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    • v.12 no.1
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    • pp.13-17
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    • 2014
  • Purpose: To determine the normative data for the correlation of spinal, pelvic parameters with foot pressure in the young subjects. Methods: The subjects of this study were 39 patients in healthy adults. The Formetric-III was used to measure of spinal alignment. The pedoscan was used to measure of foot pressure. The correlation of trunk imbalance, trunk inclination, lateral deviation with foot pressure. The foot pressure measurement was consisted of maximal/mean pressure, weight contribution. Result: There was a negative correlation of trunk inclination with Max_R. There was a negative correlation of trunk inclination with Max_R. There was a positive correlation of trunk imbalance with Max_L. There was a positive correlation of lumbar lordosis with Mean_R_front, Lt. posterior weight distribution. There was a negative correlation of lumbar lordosis with Lt., Rt. in distribution There was a negative correlation of pelvic tilt with Mean_R_front, Lt. posterior weight distribution. There was a positive correlation of pelvic tilting with Rt. weight distribution, Lt. posterior weight distribution. There was a negative correlation of pelvic torsion with Lt. weight distribution, Rt. posterior weight distribution. There was a negative correlation of pelvic rotation with Lt. weight distribution, Lt. posterior weight distribution. Conclusion: The data obtained from the study may be used for future studies related to correlation of the spinal, pelvic deviation with foot pressure.

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A Study on the Estimating Burst Pressure Distributions for Reliability Assessment of API 5L X65 Pipes (API 5L X65 배관의 신뢰도 평가를 위한 파열압력 분포 추정에 관한 연구)

  • Kim, Seong-Jun;Kim, Dohyun;Kim, Cheolman;Kim, Woosik
    • Journal of the Korean Society for Quality Management
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    • v.48 no.4
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    • pp.597-608
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    • 2020
  • Purpose: The purpose of this paper is to present a probability distribution of the burst pressure of API 5L X65 pipes for the reliability assessment of corroded gas pipelines. Methods: Corrosion is a major cause of weakening the residual strength of the pipe. The mean residual strength on the corrosion defect can be obtained using the burst pressure code. However, in order to obtain the pipe reliability, a probability distribution of the burst pressure should be provided. This study is concerned with estimating the burst pressure distribution using Monte Carlo simulation. A response surface method is employed to represent the distribution parameter as a model of the corrosion defect size. Results: The experimental results suggest that the normal or Weibull distribution should be suitable as the probability distribution of the burst pressure. In particular, it was shown that the probability distribution parameters can be well predicted by using the depth and length of the corrosion defect. Conclusion: Given a corrosion defect on the pipe, its corresponding burst pressure distribution can be provided at instant. Subsequently, a reliability assessment of the pipe is conducted as well.

Evaluation of spatial pressure distribution during ice-structure interaction using pressure indicating film

  • Kim, Hyunwook;Ulan-Kvitberg, Christopher;Daley, Claude
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.6 no.3
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    • pp.578-597
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    • 2014
  • Understanding of 'spatial' pressure distribution is required to determine design loads on local structures, such as plating and framing. However, obtaining a practical 'spatial' pressure distribution is a hard task due to the sensitivity of the data acquisition frequency and resolution. High-resolution Pessure-Idicating Flm (PIF) was applied to obtain pressure distribution and pressure magnitude using stepped crushing method. Different types of PIF were stacked at each test to creating a pressure distribution plot at specific time steps. Two different concepts of plotting 'spatial' pressure-area curve was introduced and evaluated. Diverse unit pixel size was chosen to investigate the effect of the resolution in data analysis. Activated area was not significantly affected by unit pixel size; however, total force was highly sensitive.

Quantitative Evaluation of Driver's Postural Change and Lumbar Support Using Dynamic Body Pressure Distribution (동적 체압 분포를 이용한 운전 자세 변화와 요추지지대의 정량적 평가)

  • Na, Seok-Hui;Im, Seong-Hyeon;Jeong, Min-Geun
    • Journal of the Ergonomics Society of Korea
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    • v.22 no.3
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    • pp.57-73
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    • 2003
  • Although body pressure distribution is sensitive to movements and is relatively simple to measure even in small space, there are few researches involving applications to driver's posture and its change. The main objective in this study is the application of body pressure distribution measurements for the prediction of the driver's posture and its change. This requires quantitative analyses of the dynamic body pressure distribution, which is the change of body pressure distribution with time. The experiment involved 16 male subjects who drove for 45 minutes in a seating buck. Measurement time, stature group, and lumbar support prominence were selected as independent variables, with subjective ratings of driver's discomfort, body posture data of hip, torso. knee angle, and body pressure data variables as dependent variables. The body pressure change variables and subjective ratings were found to increase as the measurement time increased and body pressure ratio variables reflected the torso angle. From the results and analysis of the body posture data and subjective rating results, it was predicted that the seats and the design of the lumbar supports used in the experiment was not fit for tall subjects, which could also be confirmed through the body pressure distribution data.

Development of a Body Pressure Distribution Measuring Equipment for an Automobils Seat (자동차용 시트의 체압분포측정기 개발에 관한 연구)

  • Park, Se-Jin;Lee, Nahm-Sik;Kim, Chul-Jung;Lee, Soon-Yo
    • Journal of Korean Institute of Industrial Engineers
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    • v.19 no.3
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    • pp.113-121
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    • 1993
  • The pressure distribution between body and seat surface has been considered as one of the most important factors which affect seation comfort. The pattern of body pressure distribution has been an index of measuring comfort of an automobile seat. There has been numerous studies that measured the body pressure distribution. But, studies have many problems(pressure distortion, resolution, reliability, portability, usability, and shape fitness) in measuring the body pressure distribution. In this study, the new body pressure distribution measuring equipment has been developed by using the thin, flat, and polymer-film devices known as Force Sensing Resistors(FSRs) in order to solve those problems.

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The Gasoline Atomization Characteristics and Static Pressure Distribution of Tapered Nozzle Swirl Spray (경사노즐 선회분사기의 가솔린 미립화 및 분무 내부 압력 분포)

  • Moon, Seok-Su;Choi, Jae-Joon;Bae, Choong-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.3
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    • pp.283-291
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    • 2007
  • The static pressure distribution, atomization characteristics and velocity distribution of tapered nozzle swirl spray is analyzed and then compared with original swirl spray. The static pressure distribution inside the swirl spray is measured using a piezoresistive pressure transducer. Phase Doppler anemometry (PDA) is applied to measure and analyze the droplet size and velocity distribution of tapered nozzle and original swirl spray. The static pressure inside the spray shows the lower value compared to the atmospheric pressure and this pressure drop is getting attenuated as the taper angle is increased. The droplet size of tapered nozzle spray shows similar value compared to the original swirl spray at the horizontal mainstream while it shows increased value at vertical mainstream. The deteriorated atomization characteristics of tapered nozzle spray is improved by applying high fuel temperature injection without causing the spray collapse. The velocity results show that the larger portion of fuel is positioned with higher injection velocity, and the smaller portion of fuel is positioned with lower injection velocity with causing spatially non-uniform mixture distribution.

A Study on the Droplet Size Distribution of Ultra High Pressure Diesel Spray on Electronic Hydraulic Fuel Injection System (전자유압식 분사계에 의한 초고압 디젤분무의 입경분포에 관한 연구)

  • Jang, S.H.;Ahn, S.K.
    • Journal of Power System Engineering
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    • v.2 no.1
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    • pp.25-30
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    • 1998
  • In order to investigate the droplet size distribution and Sauter Mean Diameter in a ultra high pressure diesel spray, fuel was injected with ultra high pressure into the environments of high pressure and room temperature by an Electronic Hydraulic Fuel Injection System. Droplet size was measured with the immersion liquid sampling technique. The immersion liquid was used a mixture of water-methycellulose solution and ethanol. The Sauter Mean Diameter decreased with increasing injection pressure, with a decrease environmental pressure (back pressure) and nozzle diameter. Increasing the injection pressure makes the fuel density distribution of the spray more homogeneous. An empirical correlation was developed among injection pressure, air density, nozzle diameter and the Sauter Mean Diameter of spray droplets.

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