• Journal of Chest Surgery
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• v.48 no.1
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• pp.59-62
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• 2015

Interventional device closure has emerged as a less invasive alternative to surgery in the management of paravalvular leakage. However, this procedure involves various problems such as a high probability of residual leakage or hemolysis. Here, we report a case of residual paravalvular leakage despite two attempts at interventional closure in a patient with a history of four previous mitral valve replacements. The fifth operation for the primary repair of paravalvular leakage was performed successfully. Careful evaluation before the procedure and specially designed devices are essential for the interventional treatment of paravalvular leakage. Surgery can be performed adequately in the management of paravalvular leakage even in high-risk patients.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.4
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• pp.266-274
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• 2016

Many researchers have been trying to improve the propulsion efficiency of a propeller. In this study, the numerical analysis is carried out for the POW(Propeller Open Water test) performance of a propeller equipped with an energy saving device called PHVC(Propeller Hub Vortex Control). PHVC is aimed to control the propeller hub vortex behind the propeller so that the rotational kinetic energy loss can be reduced. The unsteady Reynolds Averaged Navier-Stokes(URANS) equations are assumed as the governing flow equations and are solved by using a commercial CFD(Computational Fluid Dynamics) software, where SST k-ω model is selected for turbulence closure. The computed characteristic values, thrust, torque and propulsion efficiency coefficients for the target propeller with and without PHVC and the local flows in the propeller wake region are validated by the model test results of KRISO LCT(Large Cavitation Tunnel). It is concluded from the present numerical results that CFD can be a good promising method in the assessment of the hydrodynamic performance of PHVC in the design stage.

• Journal of Biomedical Engineering Research
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• v.17 no.1
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• pp.43-48
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• 1996

We investigated the energistics of the physiological heart model by comparing predictive indexes of the myocardial oxygen consumption (MOC), such as tension-time index (R), tension-time or force-time inteual (FTI), rate-pressure product (RPP), pressure-work index, and systolic pressure-volume area (PVA) when using the electro-hydraulic left ventricular device (LVAD). We developed the model of LVAD incorporated the closed-loop cardiovascular system with a baroreceptor which can control heart rate and time-varying elastance of left and right ventricles. On considering the benefit of the LVAD, the effects of various operation modes, especially timing of assistance, were evaluated using this coupled computer model. Overall results of the computer simulation shows that our LVAD can unload the ischemic (less contractile) heart by decreasing the MU and increasing coronary flow. Because the pump ejection at the end diastolic phase of the natural heart may increase the afterload of the left ventricle, the control scheme of our LVAD must prohibit ejecting at this time. Since the increment of coronary flow is proportional to the peak aortic pressure after ventricle contraction, the LVAD must eject immediately following the closure of the aortic valve to increase oxygen availability.

• Journal of Ocean Engineering and Technology
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• v.31 no.3
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• pp.183-188
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• 2017

This paper provides numerical results for the estimation of the efficiency of KRISO energy saving devices in the design stage. A finite volume method is used to solve Reynolds averaged Navier-Stokes (RANS) equations, where the SST k-$\omega$ model is selected for turbulence closure. The propeller rotating motion is determined using a rigid body motion (RBM) scheme, which is called a sliding mesh technique. The numerical analysis focuses on predicting the power reduction by the designed KRISO devices (K-DUCT) under a self-propulsion condition. The present numerical results show good agreement with the available experimental data. Finally, it is concluded that CFD can be a useful method, along with model tests, for assessing the performance of energy saving devices for propulsion efficiency improvement.

• Archives of Plastic Surgery
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• v.41 no.1
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• pp.81-84
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• 2014

In this article, we present two cases of femoral pseudoaneurysm (PA) at the femoral arterial puncture site followed by necrotizing fasciitis, which is rare but can be fatal when not managed appropriately. PA was revealed by lower-extremity angiography and color-flow Doppler ultrasonography. Hematoma removal, thrombolysis, and bleeder ligation with Gelfoam were repeatedly performed by a vascular surgeon. When necrotizing fasciitis developed, aggressive surgical drainage and creation of a viable wound bed for reconstruction were mandatory. We adopted a vacuum-assisted closure device (Kinetics Concepts International) as the standard treatment for complicated, serious, infected PA of the puncture site. Excellent clinical outcomes were obtained.

• Journal of Magnetics
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• v.6 no.1
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• pp.36-41
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• 2001

A micromagnetic model and a single-domain model simulation programs were used to analyze the sensitivity of a $20\mu m\times 60\mu m \times 1000{\AA}$ permalloy strip as a magnetoresistance sensor with bias fields of various directions and magnitudes. The micromagnetic model agrees with the measured sensitivity data better than the single-domain model. The data show the highest peak sensitivity with the bias field at 90$^{\circ}$to the current. The peak sensitivity decreases and the peak broadens as the bias angle decreases. The simulation using the micromagnetic model shows that a bias angle smaller than 90$^{\circ}$eads to magnetization patterns which are free from closure domains or vertices over a wider range of bias fields.

• Journal of Chest Surgery
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• v.38 no.5 s.250
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• pp.396-399
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• 2005

Manual or mechanical compression followed by 4 to 8 hours of bed rest is still the standard technique for accessing site management of the femoral arterial puncture site. But these methods are often uncomfortable and delay hospital discharge. Recently, a number of new devices to achieve hemostasis have been developed. These devices uses collagen to facilitate local hemostasis. But many complications associated with the use these devices have been reported internationally. We present a case of successful treatment of Rt. femoral and Rt. popliteal arteries thrombosis caused by Angioseal.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.526-529
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• 2008

Air Conditioner has become a popular comfort providing device since two decades, whether in an office or home especially for warm and wet climate countries. The RAC (Room Air Conditioner) is widely used in various working spaces and residences. It composed of heat exchager, cross-flow fan, stabilizer, rearguider and blade of diffuser region, etc. In this study, numerical analyses based on the prediction of transient phenomena were carried out to investigate the flow characteristics in the RAC, including the impeller, the rearguider, the stabilizer and the blade of the diffuser region. Using a commercial code, FLUENT, the velocity, pressure and streamlines were obtained with unsteady, turbulent flow and no-slip condition. The angular velocities of impeller are located in the 900 rpm. Turbulent closure was achieved using a standard k-${\varepsilon}$ model. A moving reference frame (MRF) approach was adopted to simulate the flow field generated by impeller in the RAC. Results were graphically depicted with various geometrical configurations and operating conditions.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.597-600
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• 2012

본 연구의 목적은 눈 폐쇄 상태 검출 알고리즘을 개발하고, 그것을 바탕으로 모바일 환경의 졸음운전 감지 시스템을 구현하는 것이다. 개발한 알고리즘은 검출된 눈 영역의 이미지를 히스토그램 분석을 통해 실험적으로 얻은 문턱 값으로 이진화 시킨 후 운전자 눈의 폐쇄 상태를 판단한다. 구현한 시스템은 얼굴과 눈 검출이 완료된 상태에서 검출된 눈이 폐쇄 상태인지를 판단한다. 폐쇄 상태인 경우 이상태가 지속되면 시스템은 운전자가 졸음운전 상태임을 감지하고 경고해준다. 자원이 제한된 모바일의 특성상 이미지 처리의 정확성뿐만 아니라 처리속도의 효율성도 중요한데 이 특성에 맞는 알고리즘을 개발하였고, 이를 바탕으로 졸음운전 감지 시스템 구현에 성공하였다.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.4
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• pp.353-360
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• 2013

Cleft lip and palate is congenital deformity in oral and maxillofacial area. Normal soft palate has velopharyngeal closure action by connecting oral cavity and nasal cavity at rest and moving upward at swallowing and specific pronunciation. Cleft palate patients with velopharyngeal insufficiency have difficulty in mastication, swallowing and pronunciation because velopharyngeal closure is incomplete. At this time, a prosthetic device used to cover palate defects is called a palatal obturator. A palatal obturator separates oral cavity and nasal cavity and recovers pronunciation, mastication, swallowing and esthetic function. The purpose of this case study is to report the results because it reaches a satisfactory result in functional and esthetic aspects through functional impression procedures using modeling compound and tissue conditioner for restoration of a cleft palate patient with velopharyngeal insufficiency.