• 대한인간공학회지
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• 제29권4호
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• pp.639-646
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• 2010

The APAM's quantitative effectiveness and comparative study in preventing and treating pressure ulcer has not been sufficiently evaluated mainly because of uncertainty of pressure load input and lack of interpretation of dynamic perfusion recovery characteristics of soft tissue. The purpose of this paper was to quantify and analyze the alternating pressure characteristics of APAM as a preventive measure for pressure ulcers. To quantify the alternating load to human body, we introduced alternating pressure profile concept and developed parametric model of the profile. Regarding pressure level and cycle time, 3 global and 7 local periodic parameters were used to define the profile such as light, standard, typical and heavy duty profile shape. Pressure impulse ratio of light duty is the lowest but pressure fluctuation is significantly high. For the same duty shape, contact conditions are changed with alternating cycle time and more dramatically in shorter alternating cycle time conditions. We can conclude that if we use shorter alternating cycle time on APAM's operation we can get more positive effects regarding to inflated contact time condition. We proposed the quantitative methods on tissue viability study of external loading by simultaneous measurement of interface pressure and tissue perfusion with proper alternating pressure profile conditions.

• 융합정보논문지
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• 제10권11호
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• pp.98-106
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• 2020

본 연구는 급성기 종합병원 입원 욕창환자에서 욕창 중등도에 영향을 미치는 요인을 파악하기 위해 수행되었다. 입원환자의 퇴원시 욕창악화에 영향요인을 확인하기 위해 수집한 자료를 이차자료 분석하였다. 원 연구는 2017년 5월부터 2018년 11월까지 일 급성기 대학병원에 입원한 만 18세 이상의 욕창환자의 의무기록을 후향적으로 조사하여 자료수집하였다. 이차자료 분석에 입원시 욕창이 있었던 472명의 자료를 이용하였다. 욕창 중증도에 따른 영향요인을 확인하기 위하여, 표면욕창에 비해 중증욕창에 영향을 미치는 요인을 로지스틱 회귀분석을 통해 확인하였다. 연구결과 급성기 대학병원 입원 욕창환자는 전체 환자의 12.7%이었으며, 중증욕창은 그 중 19.1%이었다. 중증욕창에 영향을 미치는 요인으로 성별, 체온과 환자의 기동력이 확인되었다. 입원 욕창환자에 대한 피부관리가 필요하며, 특히 기동력이 저하된 환자에게 체위변경의 횟수 증가 및 욕창부위 압력완화를 위한 관리가 요구된다.

• Journal of Biosystems Engineering
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• 제26권3호
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• pp.245-252
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• 2001

This study was carried out to investigate the effect of three factors(dynamic load, inflation pressure and multiple passes of the tire) on the contact pressure and the soil stresses under the tire. A series of soil bin experiment was conducted with a 6.00R14 radial-ply tire for sandy loam soil. Tire contact pressure at soil surface and soil stresses at 10cm and 20cm soil depth were measured for the three levels of dynamic load(1.17kN, 2.35kN and 3.53kN), for the three levels of tire inflation pressure(103.42kPa, 206.84kPa and 413.69kPa), and for five different number of passes(1, 2, 3, 4 and 5 pass). The following results were drawn from this study 1) As dynamic load, inflation pressure and number of passes of the tire increased, tire contact pressure at soil surface and soil stresses at 10cm and 20cm soil depth increased accordingly. Thus increased in dynamic load, inflation pressure and number of passes of the tire would increase soil compaction. 2) The effect of three different factors, or dynamic load, inflation pressure and number of passes of the tire, decreased as the soil depth increase. Consequently, it was found that the soil compaction at a shallow depth in soil is larger than that at deep place in soil. 3) The increase of dynamic load and number of passes increased soil stress exponentially, but the increase of inflation pressure increased soil stress linearly. The effect of tire inflation pressure on soil stress was relatively less than that of the dynamic load. Therefore, it was concluded that dynamic load is more important factor affecting soil compaction in comparison to the inflation pressure of tire.

• Child Health Nursing Research
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• 제18권4호
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• pp.177-183
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• 2012

Purpose: This study was done to examine the incidence of pressure ulcers and associated factors, by inspecting the skin of newborn babies in a newborn unit or newborn intensive care unit (NICU). Methods: The participants were 101 newborn babies in either a newborn unit or NICU in D general hospital. The incidence of pressure ulcer was measured using the skin inspection tool for pressure ulcer, suggested by Agency for Health Care Policy and Research. Results: Incidence rate of pressure ulcer was 19.8%, and 80% of the newborns with pressure ulcers were premature babies. The commonest region of onset was the ear (36.8%), followed by the foot (31.6%), occipital region (15.8%) and knee (15.8%). Those are the regions related to external medical devices like nasal Continuous Positive Airway Pressure and Pulse Oximetry. Factors related to pressure ulcers were gestational period of 37 weeks or less, hospitalization for 7 days or more, birth weight under 2,500 g and a low level of serum albumin. Conclusion: The results of the study show that the skin and underlying tissues of premature infants is at risk for pressure-related skin breakdown. As most pressure ulcers are caused by medical devices, nursing interventions are required to prevent further aggravation of the lesions.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.106-114
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• 2003

The pressure ripple in the delivery port is caused by flow ripple, which is induced by variation of pumping chamber volume. The other reason is the reverse flow from the outlet volume produced by pressure difference between pumping chamber and outlet volume, when the pumping chamber is connected with the outlet volume. In this study, a mathematical model is presented for analyzing discharge pressure ripple, which includes vane detachment, cam ring movement , and fluid inertia effects in V-groove in the side plate. From the analysis and experiment, it was found that V-groove on the side plate, coefficient of spring supporting the cam ring, and average discharge pressure are the main factors of discharge pressure ripple in variable displacement vane pump. The theoretical results, provided in this study, were well agreed with experimental results. The analytical model to estimate the magnitude of pressure ripple in this study is expected to be used f3r the optimal design of the variable displacement vane pump.

• 한국수소및신에너지학회논문집
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• 제34권5호
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• pp.497-504
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• 2023

This study analyzes pressure distribution and pressure drop in the receptacle used in charging system of hydrogen fuel cell vehicles. The objective is to minimize receptacle-induced pressure drop by redesigning internal flow channels. Through numerical simulations, three receptacle variants are compared with a baseline case. Results show reduced pressure drop in the filter section. However, the check valve section exhibits higher pressure drop, requiring further improvement. By increasing throat diameter, pressure drop is decreased by 28% between inlet and outlet of the receptacle. This study shows the relationship between dynamic pressure and pressure drop, providing a guideline for receptacle performance optimization. The redesigned receptacle offers potential for enhancing hydrogen charging efficiency.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.135-138
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• 2002

High-speed ejection of burnt gases from the resonator cavity is essential for performance optimization of the chemical laser system. Additionally, to maintain the population of lasing species at a level for maximum optical power, the pressure within the cavity must be of order of 10 torr. In the present study, a small-scale ejector was designed and built for parametric study of its performance. High-pressure air was used as a motive gas. Measurements include schlieren visualization and pressure distribution trace near the ejector nozzle and along the diffuser downstream of the ejector. preliminary tests showed performance of the ejector is a function of parameters including mass flow rate and stagnation pressure of the motive gas, ejector nozzle area ratio, throat area of the diffuser downstream of the ejector.

• 한국기계가공학회지
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• 제11권6호
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• pp.55-61
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• 2012

In this study, it was grasped to the flow characteristics of injection nozzle installed in high pressure holder for improving productivity. Chip curling occurred during cutting process for difficult-to-cut material detracts product qualities and productivity. Among of method preventing the phenomenon, high pressure injecting cutting oil is an alterative. In this study, the optimal nozzle was designed by CFD method and it was conducted to analyse on the effect of high pressure injection on chip shape generated during cutting process and wear of insert by experimental method. As the result, it could be confirmed that high pressure injection is favorable for preventing chip curling and insert from wearing.

• 한국의류학회지
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• 제13권2호
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• pp.103-108
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• 1989

The purpose of this study was to confirm the difference of garment pressure and comfort depend on age group wearing the Korean skirt-band. A loadcell was used for measuring garment pressure, and 25 female subjects were chosen for each of young, middle, and old age groups. Garment pressure was measured in front, side, and back parts of the body. The results were as follows: 1. The younger the subjects, the greater the garment pressure. This suggests that the young age group wear the Korean skirt-band more tightly than needed. 2. The measurements of the pressure in 3 parts of the body were different. In young and middle age groups, pressure decreased from side to back, while in the old age group the order was side, back, and (rent. 3. The young age group felt high restriction of pressure. And the pressure in side part of body is the greatest among the three measurement.

• 한국유체기계학회 논문집
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• 제13권1호
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• pp.35-41
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• 2010

Experimental study on the flow field inside the nozzle for radial turbine was performed. At design point, the pressure is high and the Mach number is low at the pressure side of the nozzle inlet semi-vaneless space as the flow turns through the nozzle vanes. As the flow accelerates through the nozzle passage to the throat the pressure level at the pressure and suction sides becomes similar. The flow continued accelerating from the throat to the inlet of turbine wheel and the pressure field became uniform in the circumferential direction in the vaneless space. In high expansion ratio condition, strong favorable pressure gradient band region occurred just after the throat in the semi-vaneless space in the circumferential direction and the pressure became uniform in the circumferential direction after this band. In low expansion ratio condition, core flow acceleration is dominant after the throat and this non-uniform pressure field reached to the inlet of turbine wheel.