• Journal of Advanced Marine Engineering and Technology
• /
• v.29 no.4
• /
• pp.377-383
• /
• 2005

This paper deals with the flow characteristics of air-water two-phase flow in a vertical tube of 10mm I.D. and 600mm in length at an adiabatic condition. The obtained experimental data were covered with the liquid superficial velocity ranging from 0.095m/s to 2.56m/s. and the gas superficial velocity ranging from 0.032m/s to 21.08m/s. The effects of the gas and liquid superficial velocity on the flow pattern transitions, frictional pressure drop, and film thickness and gas-liquid interface roughness were also examined. It was found that the film thickness increased and the liquid film wave length was more longer with the liquid superficial velocity $j_L$ increasing at $j_G$ constant. It was also showed that the frictional pressure drops were experienced in three regions. namely increasing region(bubbly flow), decreasing region (Taylor bubble and slug flows) and re-increasing region (annular flow).

• Structural Engineering and Mechanics
• /
• v.59 no.5
• /
• pp.795-802
• /
• 2016

Gas pipelines are types of structures that are highly susceptible to corrosion. Sometimes, the pipes are subjected to a thinning of the wall thickness at the inside or outside wall due to erosion/corrosion. Therefore, it is important to evaluate the strength of the pipes undergoing corrosion to maintain the integrity of the piping systems. The main purpose of this study is to understand failure aspects caused by degradation of metal due to corrosion through. The ASME standard offers a relationship for the yielding pressure of the corroded pipes which was compared with the finite element results. The results demonstrate to obtain accurate results, the ASME relationship is unreliable. Moreover, pitting corrosion must be considered critical more than of other types.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.17 no.4
• /
• pp.342-349
• /
• 1988

The characteristics of flow pattern transitions in a horizontal cocurrent gas-liquid flow have been investigated by means of a statistical analysis of instantaneous pressure drop curves at an orifice. The dimensionless intensity of pressure drop fluctuation shows a sudden change during the course of flow transitions, indicating that it may be a good measure to identify the flow regime transitions. The probability density function of the curves feature a unique pattern depending upon the flow regimes and the statistical properties of the PDF also have particular ranges for each flow regime. In conclusion, the statistical analysis of instantaneous pressure drops may be a powerful tool for predicting the flow regime transitions.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.03b
• /
• pp.520-527
• /
• 2000

In the present study, the analytical approaches of vacuum consolidation with horizontal drains were proposed, For dissipating rapidly pore-water in hydraulic fills, vacuum consolidation method applied vacuum pressure in horizontal drains is developed. In the analytical approaches, the governing equation is based on two-dimensional finite strain consolidation theory and the boundary conditions of horizontal drains are considered in applying negative pore-water pressure occurred by vacuum pressure, Also, parametric studies to vacuum pressure and installation pattern of horizontal drains are carried out.

• Journal of Biosystems Engineering
• /
• v.21 no.1
• /
• pp.44-51
• /
• 1996

The purpose of this paper is to obtain the basic data for design of pressure cooling system. Static pressure drop, as a function of superficial velocity, was measured for different stacking methods and stacking heights of some fruits and vegetables. At given superficial velocity, sphericity and void fraction had a much greater influence on static pressure drop than average diameter of spherical fruits such as apple, peach, tomato and kiwi fruit. Among cylindrical vegetables such as cucumber, carrot, radish and chinese cabbage, cucumber showed different pattern of static pressure drop because of its bended shape, radish showed less static pressure drop than other vegetables because its large sizes of voids. When cucumber and spinach were stacked vertically and horizontally to air flow, a much greater static pressure drop was shown in vertical than in horizontal type, therefore static pressure drop was affected not only by void fraction but also by void shape. Also, in packed-beds of fruits and vegetables, static pressure drop could be estimated very well by Ramsins equation.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.25 no.6
• /
• pp.1045-1049
• /
• 1996

Purpose of this study was to investigate correlation between blood pressure(systolic and diastolic) and dietary Na, K intake pattern in the family members of normal and hypertension disease patients, besides patients themselves. Mean values of $systolic(126.6\pm18.0$ vs $119.3\pm17.2mmHg)$ and diastolic $(77.6\pm14.6$ vs $71.6\pm12.5mmHg)$ blood pressure in the family members of hypertension patients were significantly higher than those of normal subjects. Systolic blood pressure in normal subject group was positively correlated with age, body weight, sodium in soybean paste, and was negatively correlated with potassium in hotpepper paste, soybean paste and meats. Systolic blood pressure in the family member of hypertension patient was positively correlated with age, body weight, sodium in soybean Paste, and table salt intake, but urinary potassium excretion was negatively correlated. Diastolic blood pressure was positively correlated with age, body weight, and table salt intake, and was negatively correlated with potassium in hotpepper paste and soybean paste in normal subjects groups. In the family members of hypertension patients group, diastolic blood pressure was positively correlated with age, body weight, and table salt intake, and was negatively correlated with sodium in hotpepper Paste and soybean paste and urinary potassium excretion. In total, tendency of negative correlation between Na intake pattern and systolic blood pressure in normal subjects was much obvious than that in the family members of hypertension patients. Urinary potassium excretion in the family members of hypertension patients was also negatively correlated with both systolic and diastolic blood pressure.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.11a
• /
• pp.143-144
• /
• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.06a
• /
• pp.579-580
• /
• 2008

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1655-1660
• /
• 2004

Theoretical study has been conducted to clarify pressure characteristics of KTX(Korea Train eXpress) in tunnel. The external and internal pressure of rolling stock have been measured by using the atmospheric pressure sensors and portable data acquisition system on Seoul-Busan high speed railroad line. These pressure change may give rise to the ear-discomfort for passenger and fatigue for car body. In this study, the tunnels from 200m to 4000m in length have been chosen for the investigation of tunnel length effects. From the results of experiment, the pattern of pressure change generally agrees to RTRI's experimental result for Shinkansen. We found that there are similar patterns of external pressure variation for each critical tunnel length. The critical tunnel lengths are governed by train speed, train length and sonic velocity.

• International Journal of Automotive Technology
• /
• v.6 no.2
• /
• pp.87-93
• /
• 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.