• Journal of the Korean Society of Visualization
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• v.22 no.1
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• pp.40-48
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• 2024

This study presents an in-vitro model designed to simulate mitral valve regurgitation, aiming to compare the quantification results between Proximal Isovelocity Surface Area(PISA) and 4D Flow MRI on both fixed and valve annulus tracking(VAT) views. The in-vitro model replicates the dynamic conditions of the mitral valve in a pulsatile environment, utilizing a piston pump set at 60 bpm. Through systematic experiments and analysis, the study evaluates the accuracy and effectiveness of PISA and 4D Flow MRI in assessing regurgitation severity, considering both fixed and valve annulus tracking. The displacement length measured in echo closely resembled that of optical measurements, making it advantageous for structural analysis. VAT-4D flow MRI exhibited the smallest deviation from actual flow rate values, establishing it as most accurate method for quantitative regurgitation assessment.

• Polymer(Korea)
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• v.34 no.3
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• pp.282-288
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• 2010

The porcine small intestinal submucosa (SIS) has been widely used as a biomaterial without immuno rejection responses and hyalunonic acid (HA) can be used as biocompatible materials to regenerate tissue. We developed the SIS sponge and HA loaded SIS sponges (SIS/HA) for the possibility of the application of the tissue engineering using annulus fibrosus (AF). SEM observation shows that SIS and SIS/HA sponges have interconnected and open pores. We demonstrated the presence of HA in SIS/HA sponge from C-O functional group observed by the FTIR analysis. In conclusion, we suggest that SIS/HA sponge may be useful to tissue engineering using AF cell. This may be due to the enhanced biocompatibility and higher water retention capacity of HA.

• Polymer(Korea)
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• v.32 no.1
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• pp.26-30
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• 2008

This study was designed to investigate the effect of hybridization of synthetic/natural materials for annulus fibrosus (AF) tissue regeneration in vitro and in vivo. The synthetic/natural hybrid scaffolds were prepared using PLGA (poly (lactic-co-glycolic) acid), SIS (small intestinal submucosa) and DBP (demineralized bone particles). PLGA, PLGA/SIS(20%), PLGA/DBP(20%) and PLGA/SIS (10%)/DBP (10%) scaffold were manufactured by solvent casting/salt leaching method. Compressive strength was measured. Rabbit AF cells were isolated, cultured and seeded into experimental groups. Hydroxyproline production and DNA quantity of AP cells on each scaffold was measured at 2, 4 and 6 weeks after in vitro culture. Cell-scaffold composites were implanted subcutaneously into athymic mice. After 1,4 and 6 weeks postoperatively, specimens were taken and H&E, Safranin-O and type I collagen staining were carried out concerning formation of cartilagenous tissue. In vitro PLGA/SIS scaffold was evaluated for total collagen content (bydroryproline/DNA content) and PLGA scaffold was evaluated for compressive strength.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.82-87
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• 1983

The aging and growth of Spisula sachalinensis from Ingu over the period from December 1981 through November 1982 were studied. The rings on the shell were used as the character for age determination. The ring where the translucent zone shifts to the opaque one was regarded as an annulus. The time of its formation was estimated by monthly variations of marginal growth rate in the shell. It was formed once a year over the period from August through September. The shell length at the formation of the annulus was estimated by taking the mean shell length corresponding to each of the annual ring. From analysis of mean shell length at the formation of the annulus, von Bertalanffy's growth equation was estimated as follows; $l_t=126.38(1-e^{-0.262(t-0.656)})\;W_t=485.85(1-e^{-0.262(t-0.656)})^3$ Back-calculated shell lengths estimated from this equation was quite consistent with actual shell lengths.

• Journal of Biomedical Engineering Research
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• v.21 no.3 s.61
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• pp.295-301
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• 2000

It is known that among many factors, relative micromotion at bone/implant interfaces can hinder bone ingrowth into surface pores of an implant. Loading conditions, mechanical properties of spinal materials, friction coefficients at the interfaces and geometry of spinal segments would affect the relative micromotion and spinal stability. A finite clement model of the human lumbar spine segments (L4-L5) was constructed to investigate the mechanical sensitivity at the interfaces between bone and cage. Relative micromotion. Posterior axial displacement. bone stress, cage stress and friction force were predicted in changes of friction coefficients, loading conditions. bone density and age-related material/geometric properties of the spinal segments. Relative micromotion (slip distance in a static loading means relative micromotion in routine activity) at the interfaces increased significantly as the mechanical properties of cancellous bone, annulus fibers or/and ligaments decrease or/and as the friction coefficient at the interfaces decreases. The contact normal force at the interfaces decreased as cancellous bone density decreases or/and as the friction coefficient increases A significant increase of slip distance at anterior annulus occurred with an addition of torsion to compressive preload. Relative micromotion decreased with an increase of disc area. In conclusion. relative micromotion, stress response. Posterior axial displacement and contact normal force are sensitive to the friction coefficient of the interfaces, bone density, loading conditions and age-related geometric/material changes.

• Clean Technology
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• v.25 no.2
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• pp.161-167
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• 2019

Several types of reactors have been used during the past decade to perform fast pyrolysis of biomass. Among the developed fast pyrolysis reactors, fluidized bed reactors have been widely used in the fast pyrolysis process. In recent years, experimental studies have been conducted on the characteristics of biomass fast pyrolysis in a spouted bed reactor. The fluidization characteristics of a spouted bed reactor are influenced by particle properties, fluid jet velocity, and the structure of the core and annulus. The geometry of the spouted bed reactor is the main factor determining the structure of the core and annulus. Accordingly, to optimize the design of a spouted bed reactor, it is necessary to study the pyrolysis characteristics of biomass. However, no detailed investigations have been made of the fast pyrolysis characteristics of biomass in accordance with the geometry of the spouted bed reactor. In this study, fast pyrolysis experiments using Jatropha curcas L. seed shell cake were conducted in a conical spouted bed reactor to study the effects of reaction temperature and reactor cone angle on the product yield and pyrolysis oil quality. The highest energy yield of pyrolysis oil obtained was 63.9% with a reaction temperature of $450^{\circ}C$ and reactor cone angle of $44^{\circ}$. The results showed that the reaction temperature and reactor cone angle affected the quality of the pyrolysis oil.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.13-16
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• 2002

The Intervertebral disc is a composite structure made up of the nucleus pulposus (NP) core surrounded by the multi-layered fibers of the annulus fibrosis (AF)[1]. Water is drawn into the NP by the presence of hydrophilic proteins called proteoglycans [2]. The AF, with successive layers oriented in alternating directions, surrounds the NP. These layers are placed under tension as the NP absorbs water and swells [3]. (omitted)

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.161-164
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• 2002

대기로 배출되는 휘발성 유기화합물 중의 하나인 TCE (Trichroloethylene)를 제거하는 기술들은 설치비 및 운전비가 많이 요구되는 흡착, 응축, 소각기술 들이 있으며, 이를 대체하는 신기술로 광촉매 반응으로 유기휘발물을 상온과 상압에서 광반응시켜 제거함으로서, 설치 및 조업비 측면에서 경제적인 이점이 있다.(중략)

• Journal of Chest Surgery
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• v.18 no.3
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• pp.436-439
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• 1985

A patient of Ebstein`s anomaly underwent surgical repair on Oct. 24th, 1984. Tricuspid valve was replaced by 31mm St. Jude mechanical valve without plication of atrialized right ventricle. The annulus has been placed below the coronary sinus, with care not to damage the conduction system. But postoperatively complete heart block developed. Permanent pacemaker was implanted on his 12th POD. Now he has been followed up for 9 months. There was no hemodynamic problems yet.

• Journal of Chest Surgery
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• v.20 no.1
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• pp.182-186
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• 1987

The incidence of syphilitic aortic aneurysm was decreased now a day. We experienced a case of huge syphilitic ascending aortic aneurysm from just above portion of aortic annulus to about 1 cm below innominate artery without aortic insufficiency. Surgical correction was done by replacement of ascending aorta with woven Dacron graft under cardiopulmonary bypass. Postoperative course was uneventful and discharged 15 days after surgery with good condition.