• Title/Summary/Keyword: Over pressure

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ANALYSIS OF THE SUITABLE INJECTION PRESSURE FOR DIESEL INJECTION WITH HIGH PRESSURE

  • JEONG D. Y.;LEE J. T.
    • International Journal of Automotive Technology
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    • v.6 no.2
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    • pp.87-93
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    • 2005
  • Spray patterns were visualized using the shadowgraph method, and the droplet size and velocity were measured using PDPA for high-pressure injections up to 2,600 bars. The spray pattern and spray characteristics, such as penetration, spray width, spray angle, droplet size, injection duration, and droplet velocity, were investigated to determine the suitable injection pressure. Spray penetration, width, angle, and velocity increased continuously up to 2,600 bars with the injection pressure in a high-pressure region. The rate of improvement of the above spray characteristics, however, declined rapidly, when the injection pressure reached 2,000 bars. The injection duration and droplet size generally decreased with the increase in the injection pressure, while the rate of improvement decreased abruptly after 2,000 bars. Consequently, the improvement rate of the spray characteristics became blunt at over 2,000 bars. This means that the suitable injection pressure is around 2,000 bars.

Differences in Blood Pressure among Adults in the Community according to Blood Pressure Measurement Time and Age (지역사회 성인의 혈압측정횟수 및 연령에 따른 혈압의 차이)

  • Park, Kyung-Yeon
    • Journal of Korean Biological Nursing Science
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    • v.21 no.4
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    • pp.275-282
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    • 2019
  • Purpose: This study aimed to identify the differences in blood pressure among adults in the community according to age and time of the blood pressure measurement. Methods: This was a secondary analysis study, using data from a 2015 community health survey, conducted by the Korea Centers for Disease Control and Prevention. The data of three-time-measured blood pressure were collected from 337 subjects, 25, 35, 45, 55, 65, 75 years old, which are median ages by each age group. Results: The primary systolic pressure was significantly higher than the secondary systolic pressure (t= 3.46, p= .001) and the tertiary systolic pressure (t= 4.83, p= .001). The secondary systolic pressure was higher than the tertiary measurement (t= 2.05, p= .041). There was no significant difference between the three-time-measured values for diastolic pressure. There was a significant interaction between measurement times and age in the systoic blood pressure readings (F= 1.95, p= .036). However, there was no significant interaction between measurement times and age in the diastolic blood pressure readings (F= 1.03, p= .418). Conclusion: The findings suggest that attention must be paid to the use of blood pressure values in studies or one-time-measured clinical blood pressure values. In particular, the differences in systolic pressure readings taken at different times in the older age groups were significant. Therefore, it is more important to carefully assess blood pressure in adults over the age of 45 compared to other age groups.

A Study on the Prevalence Rate of Hypertension and the Actual Conditions of Control (일 지역 성인의 고혈압 유병률 및 관리 실태)

  • Kim, Hyeon-Ok
    • Research in Community and Public Health Nursing
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    • v.10 no.1
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    • pp.154-172
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    • 1999
  • In order to analyse the prevalence rate of hypertension and the actual conditions of control, we selected five districts out of eleven eups and myuns in Chinan Country. We administered structured questionaries to 309 adults above the age of 40, computerized the data using SPSS - PC+. More than 40.1% of adults over 40 in Chinan County have health disorders ranging from high blood pressure to hypertension including alert high blood pressure at 36.2%, relatively high. Among general characteristics, differences in the rate of hypertension were influenced by age, occupation and places of residence. Over 71 who are engaged in agriculture, who don't have jobs, who reside in Sungsu, Jungchun, Chinan-eup all have higher hypertension rates than other groups. Accordingly, the control of hypertension should be focused on these people. As a result of the control of blood pressure, the survey showed 93.0% of the subjects were checked mainly at hospitals clinics, health centers subhealth centers and community health posts more than once a year, relatively high level of blood pressure management. However, the difference between their blood pressure measurements at ordinary times and the level of blood pressure at the time of research was quite considerable. Only 47.3% of the subjects diagnosed with high blood pressure and 70.3% of the subjects with normal blood pressure recognized their blood pressure accurately 52.7% of the subjects diagnosed with high blood pressure showed errors in understanding their blood pressure at normal times. Because these errors can cause problems in the control of blood pressure, proper management should be executed through a systematic examination. As a result of the high blood pressure control condition, the average period of hypertension was 74.5( ${\pm}92.8$) months, 92.3% of the subjects were diagnosed with high blood pressure at hospitals clinics, health centers subhealth centers community health posts, but only 29.5% were examined after a general check up on high blood pressure was completed. 70.5% were diagnosed with high blood pressure only after measuring their blood pressure. 14.1% of the subjects were hospitalized because of falls influenced by high blood pressure. 33.3% attended hospitals and health centers regularily for medical treatment and this shows how low the rate of the control of blood pressure. Most people did not undergo medical treatment, because they had no painful symptoms (46.7%), they didn't need to take the medicine(28.9%), or they forget to take the medicine(20.0%). These problems in the control of hypertension were discovered in the process of diagnosing high blood pressure at health medical institutions. Many people did not recognize the need for consistent control of blood pressure. That is, although the diagnosis for high blood pressures performed at hospitals clinics, health centers subhealth centers and community health posts, was 92.3%, more than 70.5% of the subjects were not examined completely with regard to blood pressure. Accordingly, heath medical institutions must diagnose high blood pressure not only by only measuring blood pressure but also by using systematic process of examination. As for the people diagnosed with high blood pressure, one should perform consistent medical approaches and help them to recognize the importance of the continuous control of blood pressure through subject-oriented education. Problems the subjects experienced were the following numbness in the limbs easily paralyzed stitches in their shoulders which felt painful, stiff necks, occiputs felt heavy, headaches when they got up in the morning, felt dizzy when standing and moving their heads and poor eyesight. The rate of knowledge related to high blood pressure was 78.7 points, comparatively low. Whether they had normal blood pressure or hypertension made no difference. These results are not desirable. Adult-oriented education forgot the prevention and management of high blood pressure should be implemented. Hypertensive-oriented education should be especially reinforced. Because there was a difference in the level of knowledge according to age, academic career, occupation or place of residence, education related to hypertension should be intensified and focused on those over the age of 71 those who did not attend school, those who do not have jobs and are engaged in agriculture and residents living in Bugui, Jungchun regions. The degree of healthy life practice in hypertensives is poor, particularly weight control, as opposed to people who have normal blood pressure. It makes no difference in smoking, the amount of daily smoking, drinking, the control of salt because each result means that they are not practicing healthy life or modifying their life-style. The development and programs to improve a healthy life should be executed.

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Effect of trailing-edge modification over aerodynamic characteristics of NACA 0020 airfoil

  • Ethiraj, Livya;Pillai, Subramania Nadaraja
    • Wind and Structures
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    • v.33 no.6
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    • pp.463-470
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    • 2021
  • This study investigates the aerodynamic characteristics of NACA series airfoil by altering the trailing edge in the form of extended and serrated sections. This contemporary advent examined NACA 0020 airfoil experimentally at the angle of attack ranging from 0° to 45° and for the Reynolds number of 2.46 × 105. To figure out the flow behaviour, the standard average pressure distribution over the airfoil surface is estimated with 50 pressure taps. The time series surface pressure is recorded for 700 Hz of sampling frequency. The extended trailing edge of 0.1 c, 0.2 c and 0.3 c are attached to the base airfoil. Further, the triangular serration is introduced with the base length of 2 cm, 4 cm and 6 cm. Each base length with three different amplitudes of 0.1 c, 0.2 c and 0.3 c were designed and equipped with the baseline case at the trailing edge and tested. The aerodynamic force coefficient, as well as pressure coefficient are presented. The obtained data advises that modification in the trailing edge will reflect the aerodynamic characteristics and the flow behaviour over the section of a wing. Resultantly, the extended trailing edge as a thin elongated surface attached to a base airfoil without revising the main airfoil favors good lift increment. The serrated trailing edge acts as a flow control device by altering the flow pattern results to delay the stall phenomenon. Besides it, improves lift co-efficient with less amount of additional drag. This extended and serrated trailing edge approach can support for designing the future smart airfoil.

An Experimental Study on Suitable Injection pressure in High Pressure Injection Region (초고압 디젤분무의 적정분사압력에 관한 실험적 연구)

  • Jeong, D.Y.;Kim, H.J.;Lee, Jong-T.
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.812-817
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    • 2001
  • Impinging spray characteristics were investigated to find suitable injection pressure by using high pressure injection system. Spray radius and spray height were increased continuously until 2,500bar but the rate of enhancement was decreased suddenly over this injection pressure region. It is expected that the maximum suitable injection pressure of impinging spray exists at around 2,500bar.

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An Analysis on Ultra High Pressure Impinging Diesel Spray Characteristics with Impinging Distance and Impinging Angle (극초고압 디젤충돌분무의 충돌거리 및 충돌각에 대한 분무특성 해석)

  • Jeong, D.Y.;Kim, H.J.;Chung, C.M.;Lee, J.T.
    • Journal of ILASS-Korea
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    • v.8 no.4
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    • pp.17-23
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    • 2003
  • To find suitable injection pressure, ultra high pressure impinging spray characteristics were investigated with a impinging distance and a impinging angle by using high pressure injection system. As impinging distance was increased, spray penetration was decreased but spray height was increased. For increase of injection pressure, spray penetration and spray height were increased until 2,500bar. But over this injection pressure region, the rate of increase was decreased suddenly.

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A Study on Microscopic Spray Characteristics of Free Spray of Diesel with Ultra High Pressure (극초고압 디젤 자유분무의 미시적 분무특성에 관한 연구)

  • Jeong, Dae-Yong;Lee, Jong-Tai
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.6
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    • pp.7-12
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    • 2005
  • In order to analyze the microscopic spray characteristics of free spray in ultra high pressure region, the droplets size and velocity of free spray injected under atmosphere condition were measured by PDPA. As injection pressure became ultra high pressure, the droplets size was decreased continuously due to the increase of mutual reaction between droplets and air. But the decreasing rate became moderate. The velocity was increased until 250 MPa, and then decreased over that of injection pressure. It was seemed that the droplet size was similar in range of $280\~350\;MPa$, but increased in 414 MPa, even though injection pressure was increased. The microscopic spray characteristics of free spray got worse in 414 MPa.

Stress Analysis and Structural Design of FRP Pressure Vessel (복합재료 압력용기의 응력해서 및 구조설계)

  • Yun, Gwang-Jun;Kim, Tae-Uk;Jeon, Ui-Jin
    • 한국기계연구소 소보
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    • s.20
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    • pp.49-55
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    • 1990
  • Filament-Wound composite pressure vessels offer significant weight saving over the conventional metal pressure vessels. S-2 glass/epoxy pressure vessel was designed, fabricated and tested. It was considered, in the analysis that the matrix and the metal liner of FRP pressure vessel shared the internal pressure. The thicknesses of hoop and helical layers were determinded by the computer program developed for the design of FRP/Metal structural pressure vessel. The computer program increased the structural efficiency about 14% comparing with the netting analysis. The experimental measurement on the deformation by internal pressure agrees with the theoretical analysis within the accuracy of 5%.

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A study of high-power density laser welding process considering surface tension and recoil pressure (표면장력과 후압을 고려한 고에너지밀도 레이저 용접공정 해석)

  • Ha, Eung-Ji;Kim, Woo-Seung
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1190-1195
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    • 2004
  • In this study, numerical investigation has been performed on the evolution of key-hole geometry during high-energy density laser welding process. Unsteady phase-change heat transfer and fluid flow with the surface tension and recoil pressure are simulated. To model the overheated surface temperature and recoil pressure considering subsonic/sonic vapor flow, the one-dimensional vaporization models proposed by Ganesh and Knight are coupled over liquid-vapor interface. It is shown that the present model predicts well both the vaporization physics and the fluid flow in the thin liquid layer over the other model.

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A Study on Relationship between Smoking Status and Postural Measurement of Taxi Drivers in Daegu

  • Shin, Hyun Gyu
    • Korean Journal of Clinical Laboratory Science
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    • v.45 no.4
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    • pp.139-143
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    • 2013
  • In 2008, according to Statistics Korea's population over the age of 20 and 26.3% of the smokers, 73.7% were non-smokers, smokers and non-smokers by smoking of 22.0% was reported. 336 people of 255 people (75.9%) is currently also showed that smoking. Hypertension, 48 people(14.30%), the boundary type of high blood pressure 193 people (57.40%) of them, especially for high blood pressure appear as a systematic management is required. 336 people targeting taxi drivers smoking and blood pressure, and the relevance of the reserch results did not show a statistically significant difference. Current smokers of 336 people surveyed 255 people (75.90%), respectively. Men over 15 years old in Korea smoking population (1990) was reported as 73.2%, Lee 2001, according etc. Korea 61.8% of the adult male smoking rate is quite high as compared to what is reported. Taxi drivers are working in very bad working conditions. The health of a taxi driver affect the safety of customers were considered.

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