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Structure Borne Noise Analysis of a Flexible Body in Multibody System (다물체계내 유연체의 구조기인 소음해석)

  • 김효식
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.130-135
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    • 2003
  • This paper presents the method for structure borne noise analysis of a flexible body in multibody system. The proposed method is the superposition method using flexible muitibody dynamic analysis and finite element one. This method is executed in 3 steps. In the la step, time dependent quantities such as dynamic loads, modal coordinates ana gross body motion of the flexible body are calculated efficiently through flexible multibody dynamic analysis. And frequency response functions are computed using Fourier transforms of those time dependent quantities. In the 2$\^$nd/ step, acoustic pressure coefficients are obtained through structure-acoustic coupling analysis by finite element analysis. In the final step, frequency responses of acoustic pressure at the acoustic nodes are recovered through linear superposition of frequency response functions with acoustic pressure coefficients. The accuracy of the proposed method is verified in the numerical example of a simple car model.

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A Study on Design of Ultra-High-Pressure Ball Valve for Hydrogen Station (수소 충전소용 초고압 볼밸브 설계에 관한 연구)

  • Choi, Ji Ah;Ji, Sang Won;Jang, Ji Seong
    • Journal of Drive and Control
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    • v.18 no.3
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    • pp.23-29
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    • 2021
  • Hydrogen energy is the clean energy source of the future. Ultra-high-pressure hydrogen is used in hydrogen stations, with its parts being developed. On the other hand, ultra-high-pressure ball valve, which is one of its parts, depends on overseas, with the level of domestic research on this being only about 10% of advanced technology research on this abroad. In this study, the shape of an ultra-high-pressure ball valve for a hydrogen station was designed to improve its structural strength. The valve body was designed according to distance between both processed body holes along inlet and outlet ports. The designed vale body was then analyzed using ANSYS to check whether points with stress were concentrated. In addition, the valve with improved body was analyzed to confirm that the valve satisfied the design condition.

The Effect of Fitness Management Class on Body Composition, Blood Pressure and Health-related Fitness in College Women (체력관리 수업이 여자 대학생의 신체구성, 혈압 및 건강관련 체력에 미치는 영향)

  • Kim, Myoung-Su;Kim, Sung-Hee;Lee, Shin-Ho
    • Journal of Digital Convergence
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    • v.14 no.12
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    • pp.607-614
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    • 2016
  • This study investigated the effect of fitness management class on body composition, blood pressure and health-related fitness in college women. The subjects were to target college women of the 317 people to take nine semesters 2012-2016 school fitness management class, group division were divided underweight, thin-obesity, normal, normal-obesity and obesity by body mass index(BMI) and body fat(%). Fitness management classes consist of combined exercise(resistance and aerobic exercise) was conducted to exercise twice a week 75 minutes a day. Four groups except for the obese group, Fitness management class have a positive improvement effect on body weight, BMI, BF(%), muscle mass and waist circumference. In addition, five groups were positive improvement on blood pressure and health-related fitness variables. In conclusions, except for improving body composition in obese college women, fitness management classes had a positive improvement effect on body composition, blood pressure and health-related fitness in college women.

Determination of the Garment Pressure Level Using the Elastic Bands by Human Body Parts (탄성 압박 밴드를 이용한 인체 부위별 의복압 가압 수준에 관한 연구)

  • Baek, Yoon-Jeong;Choi, Jeong-Wha
    • Journal of the Korean Society of Clothing and Textiles
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    • v.32 no.10
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    • pp.1651-1658
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    • 2008
  • This study was to decided the proper garment pressure level on the human body parts. Six volunteers (female: 30-40years) put on the same types of bands, a brief, and a non-woven gown. Garment pressure was measured in regular order with the elastic band on the human body parts such as the upper arm, the waist, the thigh, and the calf. At the same time, physiological responses such as the skin blood flow rate on 2 fingers, 7 different skin temperatures, rectal temperature, heat rates, and subjective responses about the pressure sensation, thermal sensation, and humidity sensation were measured and inquired. The results were as follows; 1. The thicker subcutaneous fat thickness, the higher the mean garment pressure on pressurizing the upper arm(p<.001). Also the thicker subcutaneous fat thickness. the thicker the upper arm circumference. 2. Heart rates increased pressured the upper arm and decreased pressured the waist, the thigh, and the calf. The higher the garment pressure, the higher heart rates on all body parts were pressured. Especially lean subjects showed higher physiological load than others. 3. On pressurizing the upper arm, heart rates, rectal temperature, and mean skin temperature were higher than without pressured state and pressured other body parts.4. The proper garment pressure levels were decided 30gf/$cm^2$ for fat people, 20gf/$cm^2$ for others on the upper arms and 24gf/$cm^2$ on the calf.

The relationships of body mass index, waist-to-height ratio, and body fat percentage with blood pressure and its hemodynamic determinants in Korean adolescents: a school-based study

  • Kim, Na Young;Hong, Young Mi;Jung, Jo Won;Kim, Nam Su;Noh, Chung Il;Song, Young-Hwan
    • Clinical and Experimental Pediatrics
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    • v.56 no.12
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    • pp.526-533
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    • 2013
  • Purpose: Obesity is an important risk factor for hypertension in adolescents. We investigated the relationship of obesity-related indices (body mass index [BMI], waist-to-height ratio [WHR], and body fat percentage [%BF]) with blood pressure and the hemodynamic determinants of blood pressure in Korean adolescents. Methods: In 2008, 565 adolescents, aged 12-16 years, were examined. The %BF of the participants was measured by bioelectrical impedance analysis. Echocardiography and brachial artery pulse tracing were used to estimate the stroke volume (SV), cardiac output (CO), total vascular resistance (TVR), and total arterial compliance (TAC). Results: We noted that BMI, WHR, and %BF were positively correlated with systolic blood pressure (SBP) and diastolic blood pressure (DBP). The positive correlation between BMI and blood pressure (SBP and DBP) persisted after adjustment for WHR and %BF. However, after adjustment for BMI, the positive associations between blood pressure (SBP and DBP) and WHR as well as %BF, were not noted. With regard to the hemodynamic factors, BMI, but not WHR and %BF, was an independent positive factor correlated with SV and CO. TVR had an independent negative association with BMI; however, it was not associated with WHR or %BF. Moreover, we noted that BMI, WHR, and %BF did not affect TAC. Conclusion: In Korean adolescents, BMI had an independent positive correlation with SBP and DBP, possibly because of its effects on SV, CO, and TVR. WHR and %BF are believed to indirectly affect SBP and DBP through changes in BMI.

The effect of low glycemic index diet on body weight status and blood pressure in overweight adolescent girls: a randomized clinical trial

  • Rouhani, Mohammad Hossein;Kelishadi, Roya;Hashemipour, Mahin;Esmaillzadeh, Ahmad;Azadbakht, Leila
    • Nutrition Research and Practice
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    • v.7 no.5
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    • pp.385-392
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    • 2013
  • Although several studies have assessed the influence of the glycemic index on body weight and blood pressure among adults, limited evidence exists for the pediatric age population. In the current study, we compared the effects of low glycemic index (LGI) diet to the healthy nutritional recommendation (HNR)-based diet on obesity and blood pressure among adolescent girls in pubertal ages. This 10-week parallel randomized clinical trial comprised of 50 overweight or obese and sexually mature girls less than 18 years of age years, who were randomly assigned to LGI or HNR-based diet. Macronutrient distribution was equivalently prescribed in both groups. Blood pressure, weight and waist circumference were measured at baseline and after intervention. Of the 50 participants, 41 subjects (include 82%) completed the study. The GI of the diet in the LGI group was $42.67{\pm}0.067$. A within-group analysis illustrated that in comparison to the baseline values, the body weight and body mass index (not waist circumference and blood pressure) decreased significantly after the intervention in both groups (P = 0.0001). The percent changes of the body weight status, waist circumference and blood pressure were compared between the two groups and the findings did not show any difference between the LGI diet consumers and those in the HNR group. In comparison to the HNR, LGI diet could not change the weight and blood pressure following a 10-week intervention. Further longitudinal studies with a long-term follow up should be conducted in this regard.

Influence of Peer Body Shape Norm and Peer Pressure Related to Body Shape on Social Media on Body Image Over-distortion of Early Adolescent Girls (소셜미디어 내의 또래 체형규범과 체형관련 또래압력이 초기 여자 청소년의 신체이미지 과대왜곡에 미치는 영향)

  • Jeeyeon Hong;Dooyoung Kim;Yoon Kyung Kim;Ju Hee Park
    • Human Ecology Research
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    • v.62 no.3
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    • pp.441-453
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    • 2024
  • This study aimed to explore the characteristics of early adolescent girls with an over-distorted body image and to examine the influence of peer descriptive norm and peer injunctive norm related to body shape and peer pressure for thinness on social media on body image over-distortion. The participants were 505 female adolescents in the 1st and 2nd grades of middle school. Descriptive statistics, frequency analysis, and binary logistic regression were used to analyze the data with SPSS 26.0. The results were as follows. First, the body image over-distortion group contained more 2nd-grader early adolescent girls than 1st graders and approximately three-quarters of the body image over-distortion group had previously attempted to lose weight. Second, peer pressure for thinness on social media significantly predicted whether early adolescent girls were in the body image over-distortion group compared to the non-distortion group. These outcomes suggest that it is necessary to create a social media culture that encourages early adolescent girls to have a realistic and healthy body shape. The results also highlight the importance of developing social media literacy education programs that inform early adolescents of the potential harm of negative comments on social media, and teach them how to recognize and dismiss indiscriminate and harmful comments and contents on social media.

A Study on the Fabrication and Electrical Characteristics of Hydraulic Pressure Sensors by Using Ceramics Materials (세라믹소재를 이용한 해수압센서 제작 및 전기적 특성 연구)

  • Park, Sung-Hyun;Kim, Eun-Sup;Jung, Jung-Kyun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.6
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    • pp.384-389
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    • 2015
  • In this paper, we fabricated ceramic body and sapphire wafer in order to develop a hydraulic pressure sensor with high sensitivity and high temperature stability. The sapphire wafer was adopted with a membrane of capacitance ceramic pressure sensor. The capacitance value of the sensor for the finite element analysis(FEM) showed a linear pressure characteristics. Membrane was processed with a diameter of 32.4 mm and a thickness of 1 mm by using alumina powders. Ceramic body was processed with a diameter 32.4 mm and a thickness 5 mm. The capacitance pressure sensor was made with high heat treatment of the ceramic body and the sapphire wafer. Initially capacitance of the pressure sensor was 50 pF and a capacitance of 110 pF was measured from 5 bar pressure. Output voltage of 5 V was appeared at 5 bar pressure.

Factors Predicting the Interface Pressure Related to Pressure Injury in Intensive Care Unit Patients (중환자실 환자의 욕창 관련 경계압력 예측요인)

  • Shine, Ji Seon;Kim, Soo Jin;Lee, Ji Hyun;Yu, Mi
    • Journal of Korean Academy of Nursing
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    • v.47 no.6
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    • pp.794-805
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    • 2017
  • Purpose: Interface pressure is a factor that contributes to the occurrence of pressure injuries. This study aimed to investigate interface pressure at common sites of pressure injury (occipital, gluteal and peritrochanteric areas), to explore the relationships among risk factors, skin condition and interface pressure, and to identify risk factors influencing interface pressure. Methods: A total of 100 patients admitted to the intensive care unit were enrolled at a tertiary teaching hospital in Korea. Interface pressure was recorded by a scanning aid device (PalmQ). Patient data regarding age, pulmonary disease, Braden Scale score, body mass index, serum albumin, hemoglobin, mean blood pressure, body temperature, and oxygen saturation were included as risk factors. Data collected from July to September 2016 were analyzed using binary logistic regression. Results: The mean interface pressure of the occipital, gluteal, and right and left peritrochanteric areas were 37.96 (${\pm}14.90$), 41.15 (${\pm}16.04$), 53.44(${\pm}24.67$), and 54.33 (${\pm}22.80$) mmHg, respectively. Predictive factors for pressure injuries in the occipital area were age ${\geq}70$ years (OR 3.45, 95% confidence interval [CI]: 1.19~9.98), serum albumin deficit (OR 2.88, 95% CI: 1.00~8.26) and body temperature ${\geq}36.5^{\circ}C$ (OR 3.12, 95% CI: 1.17~8.17); age ${\geq}70$ years (OR 2.81, 95% CI: 1.10~7.15) in the right peritrochanteric area; and body temperature ${\geq}36.5^{\circ}C$ (OR 2.86, 95% CI: 1.17~6.98) in the left peritrochanteric area. Conclusion: Our findings suggest that old age, hypoalbuminemia, and high body temperature may be contributory factors to increasing interface pressure; therefore, careful assessment and nursing care of these patients are needed to prevent pressure injury. Further studies are needed to establish cutoff values of interface pressure for patients with pressure ulcers.