• Journal of Mechanical Science and Technology
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• v.17 no.9
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• pp.1316-1323
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• 2003

This paper presents a structural analysis on the rigid and deformed motion of the leaflet induced by the blood flow required in the design of a bileaflet mechanical heart valve (MHV) prosthesis. In the study on the design and the mechanical characteristics of a bileaflet mechanical heart valve, the fluid mechanics analysis on the blood flow passing through leaflets, the kinetodynamics analysis on the rigid body motion of the leaflet induced by the pulsatile blood flow, and the structural mechanics analysis on the deformed motion of the leaflet are required sequentially and simultaneously. Fluid forces computed in the previous hemodynamics analysis on the blood flow are used in the kinetodynamics analysis on the rigid body motion of the leaflet. Thereafter, the structural mechanics analysis on the deformed motion of the leaflet follows to predict the structural strength variation of the leaflet as the leaflet thickness changes. Analysis results show that structural deformations and stresses increase as the fluid pressure increases and the leaflet thickness decreases. Analysis results also show that the leaflet becomes structurally weaker and weaker as the leaflet thickness becomes smaller than 0.6 mm.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.4
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• pp.5-12
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• 2003

This paper discusses about the thickness effects on the structural durability of a bileaflet mechanical heart valve (MHV). In the study on the design and the mechanical characteristics of a bileaflet mechanical heart valve, the fluid mechanics analysis on the blood flow passing through leaflets, the kinetodynamics analysis on the rigid body motion of the leaflet induced by the pulsatile blood flow, and the structural mechanics analysis for the deformed leaflet are required sequentially and simultaneously. Fluid forces computed in the fluid mechanics analysis on the blood flow are used in the kinetodynamics analysis for the leaflet motion. Thereafter, the structural mechanics analysis for the deformed leaflet follows to predict the structural strength variation of the leaflet as the leaflet thickness changes. Analysis results show that structural deformations and stresses increase as the fluid pressure increases and the leaflet thickness decreases. Analysis results also show that the leaflet becomes structurally weaker and weaker as the leaflet becomes thinner and thinner.

• Proceedings of the Korea Society of Design Studies Conference
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• 1998.10a
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• pp.80-81
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• 1998

• Proceedings of the Korea Society of Design Studies Conference
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• 1999.10a
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• pp.86-87
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• 1999

그동안 다양한 상품과 폭넓은 가격대, One-Stop쇼핑을 무기로 유통업계의 총아로 군림해온 백화점 업계의 위상이 크게 위협받고 있다. 때문에 IMF 체제에 유통시장 환경에서 살아남기 위해 최선의 심혈을 기울이는 것은 어찌보면 당연한 결과이다. (중략)

• Journal of East-West Nursing Research
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• v.19 no.1
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• pp.23-29
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• 2013

Purpose: This study was conducted to investigate how information using leaflet will affect anxiety of inpatients undergoing endoscopic examination. Methods: Non-equivalent control group with a pre-post test design was used. Subjects were selected from inpatients of D hospital in B city for endoscopic examination from May 1 to July 31, 2009. Forty subjects were assigned to either control or experimental group. The Leaflet developed by authors was used as an educational material. Johnson's visual analogue scale, blood pressure, and pulse were used to measure anxiety. Results: The experimental group informed with the leaflet showed less subjective anxiety than control group without the leaflet (p=.008). Experimental group informed with the leaflet showed less objective anxiety measured by systolic blood pressure, diastolic blood pressure, and heart rate than control group without the leaflet (p=.004, .014, and .009, respectively). Conclusion: Giving information using leaflet to the patient before endoscopy may be applicable as a nursing intervention to reduce anxiety. Further studies are needed to generalize the results of this study.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.109-112
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• 1997

The Hydrodynamic performance of the trileaflet polymer prosthetic valves depends on the design of the leaflet and the physical properties of the leaflet membrane. In order to study the effect of leaflet membrane elasticity on the hemodynamic performance of trileaflet prosthetic valve, leaflet membranes are manufactured using two different polymers - Biospan and Tecoflex SG-93A. The hemodynamic performance parameters are measured under steady and physiological pulsatile flow, and compared with monoleaflet polymer valve(floating valve) and bileaflet mechanical valve(St. Jude Medical valve). Well designed trileaflet valve shows the lowest mean pressure drop among the tested valves. The trileaflet valves with Biospan membrane show lower pressure drop and back low comparing to those with Tecoflex membrane. More elastic membrane may provide wide opening area during systole and close membrane ree edge contact during diastole. Durability of trileaflet valves are also tested in vitro. Trileaflet valves with non-uniform membrane thickness ail within 17 days because of stress concentration. Trileaflet polymer valves with uniform membrane thickness perform well over 55 days without failure.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.26 no.2
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• pp.127-135
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• 2019

Purpose: The purpose of this study was to develop an informational leaflet on emergency care and to explore effects of facilitative nurse-patient interaction behavior using an informational leaflet on patient satisfaction with nurse-patient interaction behavior, patient anxiety, and patient satisfaction with use of emergency care. Methods: This study was a quasi-experimental study that applied a nonequivalent control-group posttest-only design. The participants were 81 patients who visited the emergency department of a hospital in Korea; the experimental group (n=40) received facilitative nurse-patient interaction behavior using an informational leaflet, and the control group (n=41) received care under routine protocols without an information leaflet. The effects of the two groups were analyzed using an independent t-test with SPSS computer program. Results: Patient satisfaction with nurse-patient interaction behavior and use of emergency care in the experimental group were significantly higher than in the control group. Patient anxiety related to using emergency care in the experimental group was significantly lower than the control group. Conclusion: Therefore, facilitative nurse-patient interaction behavior using an informational leaflet to the patient may be useful interventions that are easily implemented by nurses in emergency settings.

• Korean Journal of Computational Design and Engineering
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• v.6 no.1
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• pp.59-68
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• 2001

This paper investigates the structural analysis and design of mechanical heart valve through the numerical analysis methodology. In a numerical analysis methodology application to the thickness minimization structural design of mechanical heart valve, fluid analysis is performed for the blood flow through a bileaflet mechanical heart valve. Simultaneously the kinetodynamic analysis is carried out to obtain the appropriate structural condition for the structural analysis. Thereafter the structural static analysis is also carried out to confirm the thickness minimization structural condition(minimum thickness shape of leaflet).

• Journal of Mechanical Science and Technology
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• v.19 no.9
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• pp.1761-1772
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• 2005

In blood flow passing through the mechanical heart valve (MHV) and elastic blood vessel, hemolysis and platelet activation causing thrombus formation can be seen owing to the shear stress in the blood. Also, fracture and deformation of leaflets can be observed depending on the shape and material properties of the leaflets which is opened and closed in a cycle. Hence, comprehensive study is needed on the hemodynamics which is associated with the motion of leaflet and elastic blood vessel in terms of fluid-structure interaction. In this paper, a numerical analysis has been performed for a three-dimensional pulsatile blood flow associated with the elastic blood vessel and curved bileaflet for multiple cycles in light of fluid-structure interaction. From this analysis fluttering phenomenon and rebound of the leaflet have been observed and recirculation and regurgitation have been found in the flow fields of the blood. Also, the pressure distribution and the radial displacement of the elastic blood vessel have been obtained. The motion of the leaflet and flow fields of the blood have shown similar tendency compared with the previous experiments carried out in other studies. The present study can contribute to the design methodology for the curved bileaflet mechanical heart valve. Furthermore, the proposed fluid-structure interaction method will be effectively used in various fields where the interaction between fluid flow and structure are involved.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.247-248
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• 1998

The effect of unattached valve leaflet on flow field downstream of a floating and flapping polyurethane heart valve prosthesis was investigated. With a triggering system and a time-delay circuit the instantaneous velocity field downstream of the valve was measured by particle image velocimetry (PIV) in conjunction with the opening posture of a flexible valve leaflet during a cardiac cycle. Reynolds shear stress distribution was calculated from the velocity fields and wall shear stress was directly measured by hot-film anemometry (HFA). The floating motion of the valve leaflet resulted in the reduction of pressure drop and recirculating flow region downstream of the valve.