• Title/Summary/Keyword: pressure modification factor

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Structural Design of Basement Exterior Wall using Modification Factor (보정계수를 이용한 지하외벽의 구조설계)

  • Kim, Dong-Gun;Kim, Young-Chan
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.6 no.3
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    • pp.159-165
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    • 2002
  • Currently structural design of basement exterior wall is based on the assumption of boundary condition of plate, which may lead to erroneous results. In this study, the behavior of basement exterior wall subject to earth pressure and hydraulic pressure is investigated using linear finite element analysis. Parametric studies are conducted to investigate the variation of moment and shear force according to column-to-wall stiffness and aspect ratios. Using these numerical results, modification factors applicable to the design of basement exterior wall are presented. Design example is illustrated, showing satisfactory results.

A Nested Case-Control Study on the High Normal Blood Pressure as a Risk Factor of Hypertension in Korean Middle-aged Men (중년 남성에서 고정상혈압에 의한 고혈압발생 위험 규명을 위한 코호트내 환자-대조군 연구)

  • Ahn, Yoon-Ok;Bae, Jong-Myon
    • Journal of Preventive Medicine and Public Health
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    • v.32 no.4
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    • pp.513-525
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    • 1999
  • Objectives : High-normal blood pressure' is a factor influencing decision to initiate targeted intensive intervention strategy in westernized populations. JNC-VI offered the vigorous lifestyle modification for persons with 'high-normal blood pressure', who could be early detected. As a hypertension seems to be the result of multiple genetic factors operating in concert with associated environmental factors, it will be necessary to identify the high-normal blood pressure as a risk factor of hypertension for applying primary prevention strategy in Korean people. Methods : Although cohort study design might be adequate to recruit incidence cases, to keep time sequence of events, and to prevent information bias, nested case-control study was chosen for avoiding measurement errors because hypertension is a benign disease. Source population was the 'Seoul Cohort' participants and follow-up was done by using Korea Medical Insurance Corporation's database on the utilization of health services from 1 Jan93 to 30Jun97. Incidence cases were ascertained through the chart review, telephone contacts, and direct blood pressure measurements. Controls included the pairing of 4 individuals to each case on the basis of age. Results : As 75% of 247 incident cases had high-normal blood pressure, the crude odds ratio for hypertension was 2.04 (95% CI 1.47-2.83). Another statistically significant risk factors of hypertension were body mass index, dietary fiber, alcohol consumption, weekly activity and history of quitting smoking. The multivariate odds ratio of high-normal blood pressure adjusted for all risk factors was 1.84 (95% CI 1.31-2.56). Among high-normal blood pressure group, body mass index, weekly ethanol amounts, weekly physical activity, and dietary fiber except history of quitting smoking were still risk factors of hypertension. Conclusion : 'High-normal blood pressure' is a risk factor for hypertension in Korean middle-aged men, which represents that the vigorous lifestyle modification for persons with 'high-normal blood pressure' is need.

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A Method of ROL Improvement for the Motor Operated Gate Valve Operated in the High Differential Pressure Condition (고차압에서 운전되는 모터구동 게이트밸브의 부하율 향상 방안)

  • Kim, D.W.;Yoo, S.Y.
    • The KSFM Journal of Fluid Machinery
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    • v.8 no.1 s.28
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    • pp.16-22
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    • 2005
  • This paper presents the method of ROL(Rate Of Loading) improvement for the Motor Operated Gate Valve operated in high differential pressure condition. ROL is one of the most important evaluation parameters for the valve ability. It is close to correlation in stem factor (SF) and appears different value by the differential pressure of fluid. ROL and SF are analyzed by the static test and dynamic test. The obtained result show that the modification of stem factor is very important factor for the ROL improvement. In order to obtain the same value of SF between static and dynamic test, stem and stem nut should be combined appropriately by the repetition test.

A Study on the Surface Temperature Rise in Spur Gear Part I - Flash Temperature (Spur Gear의 표면온도상승에 관한 연구 Part I - Flash Temperature)

  • 김희진;문석만;김태완;구영필;조용주
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2000.06a
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    • pp.251-257
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    • 2000
  • A numerical simulation of the temperature rise for sliding surface in dry contact is based on Jaeger's formula combined with a calculated heat input. A gear tooth temperature analysis was performed. The pressure distribution has the Hertzian pressure distribution on the heat source. The heat partition factor is calculated along line of action. A Temperature distribution of tooth surface is calculated about before and after profile modification. A Temperature of addendum and deddendum in modified gear have reduced.

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The Study for Estimation of the Surface Temperature Rise in Spur Gear Tooth (Spur Gear 치면의 표면상승온도 예측에 관한 연구)

  • 김희진;구영필;조용주
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.2
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    • pp.331-337
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    • 2001
  • A numerical simulation of the temperature rise for sliding surface in dry contact is based on Jaegers formula combined with a calculated heat input. A gear tooth temperature analysis was performed. The pressure distribution has the Hertzian pressure distribution on the heat source. The heat partition factor is calculated along ling of action. A Temperature distribution of tooth surface is calculated about before and after profile modification. A Temperature of addendum and deddendum in modified gear have reduced.

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A Method of ROL Improvement for the Motor Operated Gate Valve Operating in the High Differential Pressure Condition (고차압에서 운전되는 모터구동게이트밸브의 부하율 향상 방안)

  • Kim, D.W.;Park, S.G.;Hong, S.Y.;Yooh, S.Y.
    • 유체기계공업학회:학술대회논문집
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    • 2003.12a
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    • pp.562-567
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    • 2003
  • This paper presents the method of Rate of Loading(ROL) improvement for the Motor Operated Gate Valve operating in high differential pressure condition. The character of ROL and Stem Factor is analyzed. Static test and dynamic test were performed and acquired the diagnosis signal for the valve closing stroke. The result of this study is the modification of stem factor is very important factor for the ROL improvement. In order to obtain the same value of dynamic test thread friction coefficient stem and stem nut should be combined appropriately.

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A study on strength of internal gear (내접치차의 강도에 관한 연구)

  • 정태형
    • Journal of the korean Society of Automotive Engineers
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    • v.6 no.3
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    • pp.45-54
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    • 1984
  • Bending strength of an internal gear tooth is discussed as tooth form factor taking into account the actual stress magnitude. Stress analysis was carried out by the finite element method(FEM) for the calculation of tooth form factor of an internal gear. This paper also investigated the influences of number of teeth and addendum modification coefficient of the internal gear and the influences of number of teeth, addendum modification coefficient, pressure angle, radius of rounding of tooth tip, and bottom clearance coefficient of the pinion-shaped cutter on tooth form factor of internal gear. Generalizing the resultant data, a simple formula for the tooth form factor of an internal gear was derived for the calculation of tooth bending strength of an internal gear.

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Effect of coadministration of enriched Korean Red Ginseng (Panax ginseng) and American ginseng (Panax quinquefolius L) on cardiometabolic outcomes in type-2 diabetes: A randomized controlled trial

  • Jovanovski, Elena;Smircic-Duvnjak, Lea;Komishon, Allison;Au-Yeung, Fei (Rodney);Sievenpiper, John L.;Zurbau, Andreea;Jenkins, Alexandra L.;Sung, Mi-Kyung;Josse, Robert;Li, Dandan;Vuksan, Vladimir
    • Journal of Ginseng Research
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    • v.45 no.5
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    • pp.546-554
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    • 2021
  • Background: Diabetes mellitus and hypertension often occur together, amplifying cardiovascular disease (CVD) risk and emphasizing the need for a multitargeted treatment approach. American ginseng (AG) and Korean Red Ginseng (KRG) species could improve glycemic control via complementary mechanisms. Additionally, a KRG-inherent component, ginsenoside Rg3, may moderate blood pressure (BP). Our objective was to investigate the therapeutic potential of coadministration of Rg3-enriched Korean Red Ginseng (Rg3-KRG) and AG, added to standard of care therapy, in the management of hypertension and cardiometabolic risk factors in type-2 diabetes. Methods: Within a randomized controlled, parallel design of 80 participants with type-2 diabetes (HbA1c: 6.5-8%) and hypertension (systolic BP: 140-160 mmHg or treated), supplementation with either 2.25 g/day of combined Rg3-KRG + AG or wheat-bran control was assessed over a 12-wk intervention period. The primary endpoint was ambulatory 24-h systolic BP. Additional endpoints included further hemodynamic assessment, glycemic control, plasma lipids and safety monitoring. Results: Combined ginseng intervention generated a mean ± SE decrease in primary endpoint of 24-h systolic BP (-3.98 ± 2.0 mmHg, p = 0.04). Additionally, there was a greater reduction in HbA1c (-0.35 ± 0.1% [-3.8 ± 1.1 mmol/mol], p = 0.02), and change in blood lipids: total cholesterol (-0.50 ± 0.2 mmol/l, p = 0.01), non-HDL-C (-0.54 ± 0.2 mmol/l, p = 0.01), triglycerides (-0.40 ± 0.2 mmol/l, p = 0.02) and LDL-C (-0.35 ± 0.2 mmol/l, p = 0.06) at 12 wks, relative to control. No adverse safety outcomes were observed. Conclusion: Coadministration of Rg3-KRG + AG is an effective addon for improving BP along with attaining favorable cardiometabolic outcomes in individuals with type 2 diabetes. Ginseng derivatives may offer clinical utility when included in the polypharmacy and lifestyle treatment of diabetes. Clinical trial registration: Clinicaltrials.gov identifier, NCT01578837;

The Review of Studies on Pressure Drop and Heat Transfer In Microchannels

  • Hwang, Yun-Wook;Kim, Min-Soo
    • International Journal of Air-Conditioning and Refrigeration
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    • v.13 no.1
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    • pp.51-60
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    • 2005
  • This paper reviews the studies on the pressure drop and the heat transfer in microchannels. Although a lot of studies about the single-phase flow have been done until now, conflicting results are occasionally reported about flow transition from laminar flow to turbulent flow, friction factor, and Nusselt number. Some studies reported the early flow transition due to relatively greater wall effect like surface roughness, but the other studies showed that the flow transition occurred at the Reynolds number of about 2300 and the early flow transition might be due to less accurate measurement of the channel geometry. Also, there have been arguments whether the conventional relation based upon continuum theory can be applied to the fluid flow and the heat transfer in microchannels without modification or not. The studies about the two-phase flow in microchannels have been mostly about investigating the flow pattern and the pressure drop in rectangular channels using two-component, two-phase flow like air/water mixture. Some studies proposed correlations to predict two-phase flow pressure drop in microchannels. They were mostly based on Lockhart-Martinelli model with modification on C-coefficient, which was dependent on channel geometry, Reynolds number, surface tension, and so on. Others investigated the characteristics of flow boiling heat transfer in microchannels with respect to test parameters such as mass flux, heat flux, system pressure, and so on. The existing studies have not been fully satisfactory in providing consistent results about the pressure drop and the heat transfer in microchannels. Therefore, more in-depth studies should be done for understanding the fundamentals of the transport phenomena in the microchannels and giving the basic guidelines to design the micro devices.