• 대한간호학회지
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• 제19권3호
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• pp.285-298
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• 1989

This study investigated the effect of changing position from supine to standing upright on the circulation of young men and women. Healthy men and women ranging from age of 18 to 24 were examined. Two minutes before standing, the baseline heart rate and blood pressure were measured. Heart rate and blood pressure were recorded immediately and at every minute for 10 minutes after standing upright. Differences in heart rate and blood pressure between supine and standing upright position were evaluated. The results were summarized as follows : 1. Heart rate increased significantly immediately and at every minute for 10 minutes after standing upright. 2. Systolic blood pressure increased significantly immediately and at every minute for 4 minutes after standing upright. 3. Diastolic and mean blood pressure increased significantly immediately and at every minute for 10 minutes after standing upright. 4. Pulse pressure immediately and at every minute for 10 minutes after standing upright was significantly narrower than that of supine position. 5. There was no significant difference of heart rate between men and women after standing upright. 6. Systolic and diastolic blood pressure of men after standing upright was significantly greater than those of women. From these results, it may be concluded that heart rate, systolic, diastolic and mean blood pressure and pulse pressure increase after standing upright, and systolic and diastolic blood pressure in men is greater than those of women after standing upright.

• 한국연소학회지
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• 제21권4호
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• pp.16-22
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• 2016

Pressure and temperature variations in a shock tube have been studied numerically by changing the diameter ratio of a driven part to a driver part. There are five cases where the adopted diameter ratios are 40%, 50%, 60%, 80%, and 100% respectively. The diameter of the driver part remains unchanged meanwhile the shock tube driven part diameter increases from 40% to 100% of the driver part. In the 100% ratio case, the driver part and driven parts have the same diameter of 66.9 mm. As the diameter ratio decreases, the pressure in the shock tube and available test time are increased.

• 대한기계학회논문집B
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• 제26권6호
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• pp.823-832
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• 2002

A modified $textsc{k}$-$\varepsilon$model is proposed for calculation of transitional boundary-layer flows with changing pressure gradient. In order to develop the model for this problem, the flow is divided into three regions; pre-transition region, transition region and fully turbulent region. The effect of pressure gradient is taken into account in stream-wise intermittency factor, which bridges the eddy-viscosity models in the pre-transition region and the fully turbulent region. From intermittency data in various flows, Narashima＇s intermittency function, F(${\gamma}$), has been found to be proportional to $\chi$$^{n}$ according to the extent of pressure gradient. Three empirical correlations of intermittency factor being analyzed, the best one was chosen to calculate three benchmark cases of bypass transition flows with different free-stream turbulence intensity under arbitrary pressure gradient. It was found that the variations of skin friction and shape factor as well as the profiles of mean velocity in the transition region were very satisfactorily predicted.

• 대한의용생체공학회:의공학회지
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• 제37권1호
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• pp.39-45
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• 2016

A pressure measurement system was developed to verify magnitude and position of transferred pressure on the body surface during the intermittent pneumatic compression (IPC) which is one of the most well-known methods for the prevention of deep vein thrombosis (DVT). Eighty force sensing resistors (FSR) were arranged on a mannequin leg and a hardware controller sensed, digitized, and transferred pressure data every second while IPC was being applied. Finally, sensed pressure data were color coded and visualized on the 3D model with lab-developed software. The pressure data were also saved to files for further analysis. Using this measurement system, the changing pattern of pressure was measured on the mannequin leg by changing both chamber pressure and cuff tightness. As a result, net pressure transferred onto the body surface is dependent on chamber pressure and cuff tightness. Under the same chamber pressure, the tighter a cuff was worn, the wider compressed area was and the shorter compression cycle was. Also transferred pressure was proportional to both chamber pressure and cuff tightness.

• 기본간호학회지
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• 제2권2호
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• pp.239-251
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• 1995

The prevalence of postural hypotension among over 65 year old men is 10-30%. The postural hypotension commonly causes the discomfort such as dizziness, irritability or fainting spell, and for the result it diminishes the quality of the life of aged. Therefore the assessment and intervention of postural hypotension during changing position is very important. The purpose of this study is to investigate the effect of changing position from supine to standing upright, from supine through left lateral to standing upright, from supine through sitting to standing upright of aged. The results obtained are as follows : 1. The average systolic blood pressure of normotension group is $132.68{\pm}16.04mmHg$ at supine position. The average diastolic blood pressure of normotension group is $80.72{\pm}9.82mmHg$ at supine position. The average systolic blood pressure of hypertension group is $153.92{\pm}20.12mmHg$ at supine position. The average diastolic blood pressure of hypertension group is $93.74{\pm}15.53mmHg$ at supine position. 2. There is no significant difference of blood pressure after three different procedures as mentioned above from supine to standing upright. 3. The prevalence of postural hypotension at standing upright is 13.5% which is 18.8% of the hypertension group and 9.4% of the normotension group. There is statistical difference of the prevalence of postural hypotension between hypertension group and normotension group.

• 대한기계학회논문집B
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• 제33권5호
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• pp.365-372
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• 2009

The influence of combustor pressure on the local reaction characteristics of $CH_4$/air flames was investigated by measurements of local chemiluminescence intensity. Induced flow flames are often applied to the industrial boiler systems and incinerator in order to improve heat transfer and prevent exhaust gas leakage. In order to investigate combustion characteristics in the induced flow pattern, the combustor pressure index($P^*$) was controlled in the range of $0.7{\sim}1.3$ for each equivalence ratio in the present combustion system, where $P^*$ is defined as the ratio of absolute pressure to atmospheric one. Relationship between local reaction intensity and pressure index have been investigated by simultaneous $CH^*$, $C^*_2$ and $OH^*$ intensity measurements. It could be observed that flame length became longer with decreasing $P^*$ from $CH^*$ chemiluminescence intensity of axial direction. The mean value of $C^*_2$ and $CH^*$ chemiluminescence intensities, which indicates reaction intensity in the $CH_4$/air flames, decreased with decreasing pressure index for ${\Phi}{\leq}1$, but increased with decreasing pressure index for ${\Phi}$>1. $C^*_2/CH^*$ intensity ratio, which can be a good marker to demonstrate local equivalence ratio, was almost same for ${\Phi}{\leq}1$ regardless of pressure index change, while they showed high level for lower pressure index for ${\Phi}$>1 conditions.

• 대한기계학회논문집A
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• 제21권5호
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• pp.719-726
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• 1997

The proportional pressure control valve having versatile functions and higher performance is an essential conponent in the open loop controlled rear wheel steering gear of the four wheel steering system in a passenger car. In this study, the authors suggest a new type of load pressure feedback mechanism which can make it easy to change the range of controlled pressure without changing the capacity of solenoid. The concept of suggested mechanism, composed of the pressure chamber with throttles in series, was described. The mathematical model was derived from the rear wheel steering gear consisting of a valve and a cylinder for the purpose of analyzing the valve characteristics. And the programme for computing the characteristic of the valve was developed. Experiments were performed to confirm the performance of the valve and computations were carried out to ascertain the usefulness of the developed programme. The results from computations fairly coincide with those from experiments. And the results from experiments and computations show that the performance of new valve was as good as that of the already developed one and the new valve has advantages such as the easiness of changing the range of controlled pressure and the decrease of power loss at neutral position without the decline of performance.

• 한국수자원학회논문집
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• 제46권11호
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• pp.1103-1113
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• 2013

본 연구에서는 상수관망의 수압모니터링지점 선정방법을 제시하고 이를 모의하기 위해 단순화된 샘플관망에 적용하여 최적위치를 선정하였다. 또한, 최적의 수압모니터링지점 선정방법을 도출하고 실제 도시의 상수관망에 적용하여 모니터링 지점을 선정해보았다. 모니터링 지점선정방법은 크게 세 가지로 구분하여 계산하였다. 먼저 조도계수 변화로 인한 민감도분석, 유량변화로 인한 압력기여도분석과 민감도분석을 통하여 모니터링 지점을 선정하였다. 그리고 부정류 해석결과를 이용한 압력기여도분석과 민감도분석결과를 정류해석결과와 비교하였다. 결과를 통하여 가장 효과적이고 간편한 방법을 선정하였고 실제 상수관망에 적용하였다. 본 연구에서 제시된 모니터링 지점선정방법은 상수관망의 유지관리는 물론 누수탐지를 위한 수압관리 모니터링 지점선정방법으로 활용이 가능할 것으로 판단된다.

• 한국화재소방학회논문지
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• 제30권2호
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• pp.87-91
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• 2016

최근 우리나라의 인구구조가 표주박형태의 고령화 사회로 변화함에 따라 급사의 원인이 되는 심장질환의 발생이 고령이 될수록 증가하고 있다. 심정지나 호흡이 정지된 환자에게 사용되는 인공호흡기중 전 세계적으로 보급되고 있는 공급되는 산소의 압력만으로 자동으로 작동되는 휴대용 인공호흡기의 필요성이 증가하고 있다. 이러한 휴대용 인공호흡기의 구성품 및 인공호흡기에 중요시되는 성능요구사항에 따른 시험방법을 제시하고 그에 따른 인공호흡기 내부감압셋팅 변화조건에 따른 최적 성능요구조건에 적합한 내부 감압조건을 찾고자 한다.

• Coupled systems mechanics
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• 제9권5호
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• pp.455-471
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• 2020

This paper presents the results of the study of vertically natural frequency of tractor tires are effected by changing different ground contacts and inflation pressures using the Free Decay Method. The results show that the natural frequencies of the tire are not affected while the vertical acceleration increased strongly due to the increase of inflation pressure when the tire performs free decay vibration on rigid ground. In addition, the number of natural frequency peaks of the tire also increases with increasing tire inflation pressure. On the other hand, the natural frequencies of the tractor tire increases strongly while the vertical acceleration decreases slightly with the increase of tire inflation pressure as the tire performs free decay vibration on soft soil. Further, the natural frequencies of tire-soil system are always higher than that of tire only, and it changed with changing the soil depth. Results also show the natural frequency of tire and tire-soil system is in the range of 3.0 to 10.0 Hz that lie within the most critical natural frequency range of the human body. These findings have to be mentioned and used as design parameters of the tractor suspension system.