• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.485-501
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• 1997

Pressure control is possible driving a simple ON/OFF 3-way valve of hydraulic servo system by pulse width modulation signal. But the pressure varies according to the duty ratio and carrier frequency and repeated on-off action induces pressure fluctuation. So equations for mean pressure and ripple amplitude are theoretically derived as a function of on/off time, the system parameters which decide the pressure characteristics are arranged and they are verified by experimental study. As the result selection criteria for the major design parameters are established and the basic strategy to suppress the unnecessary fluctuation can be provided for a hydraulic pressure control system using these type of valves.

• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.2
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• pp.70-78
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• 2004

An experimental study on the pressure drop during flow boiling for pure refrigerants Rl34a and R123, and their mixture was carried out in a uniformly heated horizontal tube. Tests were run at a pressure of 0.6㎫ and in the ranges of heat flux 5-50㎾/$m^2$, vapor quality 0-100 percent and mass velocity of 150-600 kg/$m^2$s. Generally, the two-phase frictional multiplier is used to predict the frictional pressure drop during the two-phase flow boiling. The obtained results have been compared to the existing various correlations for the two-phase multiplier. Also, the frictional pressure drop was compared to a few available correlations; The Lockhart-Martinelli correlation considerally overpredicted the frictional pressure drop data for mixture as well as pure components in the entire mass velocity ranges employed in the present study, while the Chisholm correlation underpredicted the present data. The Friedel correlation was found to satisfactorily correlate the frictional pressure drop data except for a low quality region.

• Journal of Power System Engineering
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• v.14 no.4
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• pp.43-49
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• 2010

In the present study, optimization of throttle margin for high pressure turbine to be retrofitted or partially modified for power uprating or life extension in nuclear power plant, has been performed to increase the electrical output. Throttle margin for high pressure turbine is required to maintain all the time the rated power by opening more of governor valves whenever inlet pressure is decreased due to the tube plugging of steam generator. If throttle margin of high pressure turbine is too much compared to remaining lifetime, loss of electrical output due to pressure drop of governor valves is inevitable. On the contrary, if it is too little, the rated power operation can not be accomplished when inlet pressure of high pressure turbine is dropped after many years operation. So, throttle margin for high pressure turbine in nuclear power plant is compromised considering for the degradation of steam generator, governor valve capacity, manufacturing tolerance of high pressure turbine, future plan of power uprating, and remaining lifetime of power plant.

• Korean Journal of Adult Nursing
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• v.16 no.2
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• pp.183-190
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• 2004

Purpose: The purpose of this study was To exam the skin and pressure sore and To evaluate the predictive validity for the new pressure sores risk assessment scale. Method: There was finally 211 neurosurgery subject admitted in Chung-Ang Univ. Hospital from Nov, 11, 2002 to Feb, 11, 2003. Data was collected three times per week from 48-72hr after admission until incidence of pressure sores or discharge or die. Inclusion criteria were; (1) no pressure sores at admittance, (2) at least 3 times assessment, (3) adults older than 16yrs, (4) patients consent to participate in study. Result: 1. 34 case of 211 developed pressure sores(11.6%). 2. The coccyx area was the most common occurrence site of pressure sores. 3. At the cutoff point 23 of sensitivity 100%, specificity 76.3% was higher in 2003 than specificity 63.8% at the cutoff point 26 of sencitivity 100% in 1991. 4. "Moisture" of subscale for pressure sores risk factor was the strongest predictor. Conclusion: This study shows that the New Pressure Sores Risk Assessment Scale still predict the risk of developing pressure sores in neurosurgical subject.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.225-231
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• 1997

This paper reports on the theoretical study of the delivery pressure ripples of a positive displacement vane pump which is widely used for automobile power steering. Pressure ripples occur due to the flow tipples which induced cam ring profiles and reverse flow from the delivery ports. In this paper, the mathematical model for analyzing the pressure ripples has been presented, and set of the differential equationshave been solved using the Runge-Kutta method. As the results of analysis, instant ideal flow ripples, internal pressure, delivery pressure ripples, and delivery flow ripples have been presented. Internal pressure was related to delivery pressure variations, and amplitude of pressure tipples was increased with rotational speed and delivery pressure.

• Journal of Wellbeing Management and Applied Psychology
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• v.2 no.2
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• pp.13-19
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• 2019

This study is about pressure-accepting behavior of consumers attached to brands. Previous studies of the situation focused on time pressure and scarcity pressure, focusing on scarcity. The results of the study are as follows. First, consumers attached to brands were found to be relatively blunt in time pressures. This indicates that brands of consumers are attached to do not buy on impulse because of time pressure. Second, consumers attached to brands were found to be relatively under social pressure. This indicates that consumers who are attached to the brand do not buy with social pressures such as quasi-family groups. Third, consumers attached to brands were found to be relatively sensitive to scarcity pressures. Thus, a quantity-limited marketing strategy is generally more effective for consumers with high marketing effectiveness but high brand attachment. Fourth, unlike the one presented, consumers attached to the brand were found to be relatively insensitive to place pressure.

• The KSFM Journal of Fluid Machinery
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• v.15 no.3
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• pp.25-31
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• 2012

A computational study on the improvement of the pressure loss of intake system, which is located at engine manifold of the combat vehicle, has been conducted using a finite-volume-based, Reynolds-Averaged Navier-Stokes (RANS) solver. The computational result of the pressure loss through the air cleaner is in good agreement with equivalent experimental data. A parametric study was done for improving of the pressure loss of intake system over the baseline case. The effects of five primary parameters such as the height of inlet, the width of interconnection pipe, the shape of drain chamber and the diameter of filter housing were considered in this study. Consequently, this computational investigation can contribute to finding an optimal guideline for the idea of improvement in the pressure loss of intake system.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.521-526
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• 2000

Experimental study is conducted to clarify pressure variation of the passenger cabin of conventional train. These pressure variation may give rise to the ear-discomfort. Generally ear-discomfort has been considered as a problem related to high speed train. Because there is also a good progress to speed-up for conventional line, this isn't only a phenomena related to high speed train any longer. In this study, tile pressure variation of interior, gangway and exterior of saemaeul passenger car is measured using the atmospheric pressure sensors in Honam line. From the results of experiment, the pressure variation per second almost close in upon the limitation in the case of Noryong tunnel. Therefore, to accomplish speed-up for conventional train, it may be necessary to study a serial ventilating and the airtightness of carbody.

• 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.

• Research in Community and Public Health Nursing
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• v.20 no.1
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• pp.105-111
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• 2009

Purpose: The purpose of this study was to identify minimum datasets for ulcer assessment and to map the minimum datasets to paper-based nursing records for pressure ulcer care in homecare setting. Methods: To identify minimum datasets for pressure ulcer assessment, the authors reviewed four guidelines for pressure ulcer care. The content validity of the minimum datasets was assessed by three homecare nurse specialists. To map the minimum datasets to nursing records, the authors examined 107 pressure ulcer events derived from 45 pressure ulcer patients who received home nursing from two hospitals in Gyeonggi Province. Results: The minimum datasets for initial assessment were anatomical location, stage, size, tissue, exudate, condition of periwound skin, undermining, odor, and pain. 'Location' was recorded best, accounting for a complete recording rate of 98.1%. 'Exudate' and 'pain' showed the poorest record, accounting for 2.8% and 0%, respectively. The minimum datasets for progress assessment were wound size, tissue, and exudate, each accounted for 31.8%, 2.8%, and 4.7%, respectively. Conclusion: This study concluded that data on pressure ulcer assessment was not sufficient homecare and it can be improved by adopting minimum datasets as identified in this study.