• Korea-Australia Rheology Journal
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• v.21 no.1
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• pp.39-46
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• 2009

Atherosclerosis is a disease that narrows, thickens, hardens, and restructures a blood vessel due to substantial plaque deposit. The geometric models of the considered stenotic blood flow are three different types of constriction of cross-sectional area of blood vessel; 25%, 50%, and 75% of constriction. The computational model with the fluid-structure interaction is introduced to investigate the wall shear stresses, blood flow field and recirculation zone in the stenotic vessels. The velocity profile in a compliant stenotic artery with various constrictions is subjected to prescribed physiologic waveform. The computational simulations were performed, in which the physiological flow through a compliant axisymmetric stenotic blood vessel was solved using commercial software ADINA 8.4 developed by finite element method. We demonstrated comparisons of the wall shear stress with or without the fluid-structure interaction and their velocity profiles under the physiological flow condition in the compliant stenotic artery. The present results enhance our understanding of the hemodynamic characteristics in a compliant stenotic artery.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1919-1922
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• 2003

Bypass anastomosis are frequently adopted for surgical treatments. After the bypass grafting, the bypass artery is often occluded due to restenosis and/or anastomotic neointimal fibrous hyperplasia phenomena. Optimal coronary bypass anastomosis should be investigated to improve the patency for the arterial bypass techniques. The objective of this study is to investigate the influence of bypass with sequential bypass effects in the stenosed coronary artery. Numerical analyses are focused on the understanding of the flow patterns for different sequential anastomosis techniques. Blood flow field is treated as two-dimensional incompressible laminar flow. The finite volume method is adopted for discretization of the governing equations. The Carreau model is employed as the constitutive equation for blood. To find the optimal sequential bypass anastomotic configurations, the mass flow rates at the outlet of different models are compared quantitatively.

• Journal of Biomedical Engineering Research
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• v.10 no.2
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• pp.91-93
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• 1989

We have developed a monoleaflet polymer valve as an inexpensive and viable alternative, especially for short-term use in the ventricular assist device or total artificial heart. The frame and leaflet of the polymer valve were made from polyurethane, To evaluate the hemodynamic performance of the polymer valve a comparative study of flow dynamics past a polymer valve and a St. Jude Medical prosthetic valve under physiological pulsatile flow conditions in vitro was made. Comparisons between the valves were made on the transvalvular pressure drop, regurgitation volume and maximum valve opening area. The polymer valve showed smaller regurgitation volume and transvalvular pressure drop compared to the mechanical valve at higher heart rate. The results showed that the functional characteristics of the polymer valve compared favorably with those of the mechanical valve at higher heart rate.

• Journal of Chest Surgery
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• v.26 no.10
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• pp.753-760
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• 1993

The CarboMedics valve is a bileaflet prosthesis with excellent hemodynamic characteristics, but the long term surgical experience with this valve, its durability and its biocompatibility are unknown. During a 5 year period from october 1988 to July 1993, 748 prostheses [402 mitral, 261 aortic, 58 tricuspid, 27 pulmonic] were inserted in 552 patients [mean age 40.2 years]. The operative mortality was 6.6% [37/560, 13.2% in age group below 15 years and 5.7% above 15 years]. and the main causes of death were complex congenital malformation and left ventricular failure. Follow up was totaled 1182 patient- years and mean follow up was 28.3 months/patient. No structural failure has been observed. Hemorrhage was the most frequent valve related complication[1.78% / Patient-year]. Embolism occurred at a rate of 0.93% / Patient-year. There were 5 cases of valve thrombosis [0.42% / Patient-year, two fatal]. There occurred 11 late deaths[6 valve related] and 42 valve related complications. Actuarial survival at 5 years is 97.18 0.94% and actuarial complication free survival at 5 years is 89.07 1.54%. In summary, the CarboMedics valve stands for a durable valve substitute, with low valve related complications.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.16 no.1
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• pp.19-26
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• 2012

Objectives The aim of this study is to develop a cardiovascular simulator that can reproduce blood pressure pulse and blood flow similar to those of the human body. Methods In order to design a system similar to the human cardiovascular system, the required performances were determined by investigating the hemodynamic characteristics of the heart and the arterial system. Main organ to be imitated is heart in simulator. The rest of the system was minimally designed. Also, a blood pressure and blood flow measurement system was developed for measuring the results. Results The developed system showed blood pressure pulse at similar range of the human aorta. The result waveform include primary wave caused by ventricular systole except reflected wave. Conclusions The blood pressure and blow flow patterns were replicated by the simulator. These patterns were similar to those of the human body. The system will play an important role in studying pulse diagnostics.

• Journal of Biomedical Engineering Research
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• v.18 no.2
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• pp.187-196
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• 1997

The three-dimensional flow analysis using the finite volume method is presented to compare the steady flow characteristics of blood with those of blood substitutes such as water and aqueous polymer solution in an idealized double branching model. The model is used to simlllate the region of the abdominal aorta near the celiac and superior mesenteric branches. Apparent viscosities of blood and the aqueous Separan solution are represented as a function of shear rate by the Carreau model, Water and aqueoiu Separan AP-273 500wppm solution are frequently used as blood substitutes in vitro experiments. Water is a typical Newtonian fluid and blood and Separan solution are non-Newtonian fluids. Flow phenomena such as velocity distribution, pressure variation and wall shear stress distribution of water, blood and polymer solution are quite different due to differences of the rheological characteristics of fluids. Flow phenomena of polymer solution are qualitatively similar to those of blood but the phenomena of water are quite different from those of blood and polymer solution. It is recommended that a lion-Newtonian fluid which exhibits very similar rheological behavior to blood be used in vitro experiments. A non-Newtonian fluid whose rheological characteristics are very similar to those of blood should be used to obtain the meaninylll hemodynamic data for blood flow in vitro experiment and by numerical analysis

• Journal of Korean Academy of Nursing
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• v.39 no.3
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• pp.311-320
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• 2009

Purpose: This study was to analyze research reports published in Korea on cardiac rehabilitation for patients with cardiovascular disease. Methods: Based on inclusion criteria, 19 research reports were included in this review. Published year of selected articles was between 1996 and 2008. Nineteen studies were analyzed by guidelines of the cardiac rehabilitation programs done by the American Heart Association(AHA) and Scottish Intercollegiate Guidelines Network(SIGN). Results: The characteristics of patients were mostly of ischemic heart disease, 50-59 yr old, and male. Educational sessions were administered twice, and each lesson lasted less than 30 min. Exercise was done 3 times per week for 6 weeks. Most educational content were about risk factors, but there was no information, such as coping with feelings. Most exercise was performed as ROM, treadmill, and cycle ergometer. A large percentage of outcome indicators were health behavior, hemodynamic changes, and exercise capacity. There was more 'no effect' than 'positive effect' in trait anxiety and depression, whereas similar in physiologic domain. Conclusion: Various types of cardiac rehabilitation in Korea were performed by researchers. Therefore, we need to develop the standard protocol, to add psychosocial intervention, and to study cost effectiveness of cardiac rehabilitation.

• Korean Journal of Biological Psychiatry
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• v.24 no.3
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• pp.110-128
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• 2017

Electroconvulsive therapy (ECT) has been recognized effective as primary or secondary treatments for major psychiatric disorders including depression and schizophrenia, as well as psychiatric emergency such as suicide, food refusal and catatonia, and so on. Medicines used in anesthetic induction for ECT, cause various reactions in autonomous, hemodynamic, and neuromuscular systems. The anesthetics also affect the duration, threshold, and intensity of seizures evoked with electric stimuli, and thus modify the seizure quality in ECT. Individual characteristics of age, sex, weight, comorbid physical disorders, and medications should also be considered for optimal clinical response after ECT. When preparing for anesthesia, adequate anesthetic agents and muscle relaxants, and rapid recovery should be carefully considered. We conducted a case-series study to address practical issues that are frequently encountered during ECT anesthesia with reviews of updated journals in order to provide practical helps to clinicians who are preparing ECT for their patients.

• BMB Reports
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• v.48 no.3
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• pp.131-138
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• 2015

Cardiac hypertrophy is a form of global remodeling, although the initial step seems to be an adaptation to increased hemodynamic demands. The characteristics of cardiac hypertrophy include the functional reactivation of the arrested fetal gene program, where histone deacetylases (HDACs) are closely linked in the development of the process. To date, mammalian HDACs are divided into four classes: I, II, III, and IV. By structural similarities, class II HDACs are then subdivided into IIa and IIb. Among class I and II HDACs, HDAC2, 4, 5, and 9 have been reported to be involved in hypertrophic responses; HDAC4, 5, and 9 are negative regulators, whereas HDAC2 is a pro-hypertrophic mediator. The molecular function and regulation of class IIa HDACs depend largely on the phosphorylation-mediated cytosolic redistribution, whereas those of HDAC2 take place primarily in the nucleus. In response to stresses, posttranslational modification (PTM) processes, dynamic modifications after the translation of proteins, are involved in the regulation of the activities of those hypertrophy-related HDACs. In this article, we briefly review 1) the activation of HDAC2 in the development of cardiac hypertrophy and 2) the PTM of HDAC2 and its implications in the regulation of HDAC2 activity.

• Childhood Kidney Diseases
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• v.19 no.2
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• pp.71-78
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• 2015

The incidence of acute kidney injury (AKI) in critically ill pediatric patients has been reported as increasing to 25 %, depending on population characteristics. The etiology of AKI has changed over the last 10-20 years from primary renal disease to the renal conditions associated with systemic illness. The AKI in pediatric population is associated with increased mortality and morbidity, and prevention is needed to reduce the consequence of AKI. It is known that the most important risk factors for AKI in critically ill pediatric patients are clinical conditions to be associated with decreased renal blood flow, direct renal injury, and illness severity. Renal hypoperfusion leads to neurohormonal activation including renin-angiotensin-aldosterone system, sympathetic nervous system, antidiuretic hormone, and prostaglandins. Prolonged renal hypoperfusion can result in acute tubular necrosis. The direct renal injury can be predisposed under the condition of renal hypoperfusion, and appropriate treatment of volume depletion is important to prevent AKI. The preventable causes of AKI include contrast-induced nephropathy, hemodynamic instability, inappropriate mediation use, and multiple nephrotoxic insults. Given the evidence of preventable factors for AKI, several actions such as the use of protocol for prevention of contrast-induced nephropathy, appropriate treatment of volume depletion, vigorous treatment of sepsis, avoidance of combinations of nephrotoxic medications, and monitoring of levels of drugs should be recommended.