• 한국자동차공학회논문집
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• 제9권1호
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• pp.102-111
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• 2001

To describe the air flow characteristics within an air cleaner cover and mass air flow sensor (MAFS) entry region installed in a 3.0L engine air induction system, flow visualization, velocity and turbulence intensity measurements were taken in several view planes. A detailed knowledge of the interaction between the design parameters and the flow structures will enhance our understanding of the motions within the flow field and enable engineers to optimize the induction system and reduce the signal-to-noise ratio in the MAFS output. Emphasis is placed on the analysis of coherent motions and the controlling parameters which affect the air flow in the MAFS entrance region over a flow rate of 13-240 kg/hr. The high speed motion pictures illustrated that the air flow generated within the air cleaner cover under steady state condition is quite complex. In both axial and radial planes of the main passage it was found that the flow pattern is remarkably influenced by the air cleaner cover and main passage configuration. A comparison of the flow patterns and measurements in the original and modified air cleaner cover is presented. Measurements from the MAFS indicated an significant reduction in pressure drop and signal noise for the modified cover as compared with the original cover, over an air flow rate of 13-240 kg/hr.

• 한국유체기계학회 논문집
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• 제7권1호
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• pp.30-35
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• 2004

The HANARO, a multi-purpose research reactor of 30 MWth open-tank-in-pool type, has been under normal operation since its initial criticality in February, 1995. Many experiments should be safely performed to activate the utilization of the HANARO. HANARO flow simulation facility is being developed for the endurance test of reactivity control units for extended life time and the verification of structural integrity of those experimental equipments prior to loading in the HANARO. This facility is composed of three major parts; a half-core structure assembly, a flow circulation system and a support system. The flow circulation system is composed of a circulation pump, a core flow piping, a core bypass flow piping and instruments. The system is to be filled with de-mineralized water and the flow should be met the design requirements to simulate a similar flow characteristics in the core channel of the half-core structure assembly to the HANARO. This paper, therefore, presents an analytical analysis to study the flow behavior of the system. Computational flow analysis has been performed for the verification of system pressure variation through the three-dimensional analysis program with the standard $k-{\epsilon}$ turbulence model and for the verification of the structural piping integrity through the finite element method. According to the analysis results, it could be said that the design requirements and the structural piping integrity of the flow circulation system are satisfied.

• Journal of Chest Surgery
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• 제53권6호
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• pp.403-407
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• 2020

To validate the technique of the single Heartstring aortotomy for multiple off-pump venous bypass grafts (described in 2015), the results of a 38-month follow-up study of 18 patients, including high-risk patients, are presented. No early deaths or cardiac or cerebral complications occurred. During the follow-up period, 2 patients died of non-cardiac causes, and 3 developed coronary ischemia. Ischemia occurred due to late graft occlusion in 2 patients, both of whom had normal postoperative courses and correct graft flow. The presence of acute symptoms 24 months after surgery in these patients indicated that technical graft failure was unlikely. This safe technique combines the advantages of simple and reproducible revascularization, the off-pump approach, and minimal aortic manipulation.

• Journal of Korean Neurosurgical Society
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• 제58권5호
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• pp.467-470
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• 2015

A 74-year-old patient was diagnosed with a subarachnoid hemorrhage suspected from a dissecting aneurysm located at the lateral medullary segment of the posterior inferior cerebellar artery (PICA). Because perforators to the medulla arose both proximal and distal to the dissecting segment, revascularization for distal flow was essential. However, several previously reported methods for anastomosis, such as an occipital artery-PICA bypass or resection with PICA end-to-end anastomosis could not be used. Ultimately, we performed an in situ side-to-side anastomosis of the proximal loop of the PICA with distal caudal loops within a single artery, as a "closing omega," followed by trapping of the dissected segment. The aneurysm was obliterated successfully, with intact patency of the revascularized PICA.

• Journal of Chest Surgery
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• 제52권6호
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• pp.416-419
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• 2019

Flow reversal and thromboexclusion constitute a valuable alternative for aortic surgeons to have within their technical armamentarium for the treatment of aortic aneurysmal disease. Although not usually a preferred treatment for general aortic pathologies, this technique can be considered as a treatment option in select situations, such as mycotic aneurysm, a hostile surgical field, and a poor condition of the patient. Here, we present a case of extra-anatomic bypass and thromboexclusion for recurrent aortic aneurysm after previous extra-anatomic bypass and thromboexclusion surgery.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.952-957
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• 2001

The objectives of this investigation were to obtain an excellent spray by cavitation under the low injection pressure. When cavitation occurs in the nozzle hole, the atomization of the liquid jet enhanced considerably. In this experiments, a acrylic nozzle made the gap and installed the bypass in the nozzle hole was used to enhance the atomization of the liquid jet at the low injection pressure. The liquid flow in the nozzle hole was photographed by a transmitted light using a micro flash. The spray angle was measured macroscope images of PMAS and the Sauter mean diameter was measured PDA system. To measure the pressure of the nozzle hole, pressure transducer was used. The results of this study indicated that enhanced atomization of the liquid jet at the low injection pressure was obtained by making the gap and installing the bypass at the single hole nozzle.

• 한국분무공학회지
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• 제7권1호
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• pp.36-42
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• 2002

The objective of this investigation was to obtain an excellent spray at the low injection pressure. When cavitation occurred in the nozzle hole the atomization of the liquid jet enhanced considerably. In this experiments, a acrylic nozzle which was installed the gap and installed the bypass in the nozzle hole was used to enhance the atomization of the liquid jet at the few injection pressure. The liquid flow in the nozzle hole was photographed by a transmitted light using a micro flash. The spray angle was measured by macroscope images of PMAS and the Sauter mean diameter was measured by PDA system. The pressure of the notate hole was measured by pressure transducer. It was found that enhanced atomization of the liquid jet at the low injection pressure was obtained by installing the gap and the bypass at the single hole nozzle.

• Journal of Chest Surgery
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• 제24권7호
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• pp.725-731
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• 1991

Four patients with traumatic rupture of aorta underwent operative repair at Seoul national university hospital. All cases were confirmed by preoperative aortography. Rupture site was aortic isthmus or just distal to it. Operations were somewhat delayed due to the low degree of suspicion and difficulties in diagnosis: ranging from 5 hours to 8 days. Operation was performed as same manners in all cases: resection of the ruptured portion and tubular woven dacron graft interposition in conjunction with shunt or bypass procedures, TDMAC-Heparin shunt between ascending and descending aorta was used in 3 cases, and LA-femoral centrifugal pump was used in one case. There were no intraoperative or postoperative mortality. Hoarseness was developed in all patients but paraplegia or other significant complications were not found in any of patients. We concluded that 1] high degree of suspicion is essential in the early diagnosis and treatment of traumatic aortic rupture and 2] any kind of shunt or bypass procedure is necessary in operative repair of traumatic aortic rupture and use of centrifugal pump without systemic heparinization is easier and safer procedure than others for the maintenance of adequate distal flow.

• Journal of Chest Surgery
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• 제28권1호
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• pp.7-10
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• 1995

Mixed Venous oxygenation saturation[SvO2 is a variable determined in part by the externally controlled factors and in part by the patient during CPB. I monitored the SvO2 and tested it as a parameter for the regulation of pump output and as a criteria for the need of inotropics after CPB. With the help of SvO2, I increased the pump flow especially during rewarming for more optimal oxygenation of cells. After CPB, the calculated cardiac index was used as an indicator for the need of inotropic support with greater accuracy and without any clinical problems. I conclude that the SvO2 is an easily checkable variable and a good indicator for optimal oxygenation at cell level, and can be used as an objective criteria for the need of postoperative inotropic support.

• 한국자동차공학회논문집
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• 제5권1호
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• pp.1-13
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• 1997

The key point that guarantees the durability of the ceramic monolith filter is to lower peak temperature and temperature gradient inside filter during regeneration. The control of the exhaust gas flow rate into the filter, by the bypass technique of the exhaust gas, enables the gas temperature in filter to be constant for regeneration. A couple of methods, which are the ON/OFF and PID control of the bypass valve, were used for feedback control of the gas temperature. These techniques showed that the ceramic filter was regenerated perfectly under the peak temperature and peak temperature gradient limitations for durability.