• Journal of Advanced Marine Engineering and Technology
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• 제18권3호
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• pp.43-51
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• 1994

The design technique of turbo pumps has been developed due to an increasing demand from related industrial fields. But infant stage of turbomachinery in the domestic industry needs more fundamental design method. Among various types of pumps, centrifugal pump was chosen because of its wide industrial application. It is difficult to decide the correct specification of centrifugal impeller, because of its complex flow analysis at the inlet, passage and outlet. This study is limited on the impeller blade design and its related performance analysis.

• 한국수소및신에너지학회논문집
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• 제30권5호
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• pp.448-454
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• 2019

This paper presents a high-efficiency design technique for developing the serialized models of a single-channel pump based on the diameter, flow rate and head as the main performance parameters. The variation in pump performance by changing of the single-channel pump geometry was predicted based on computational fluid dynamics (CFD). Numerical analysis was conducted by solving three-dimensional steady Reynolds-averaged Navier-Stokes equations with the shear stress transport (SST) turbulence model. The tendencies of the hydraulic performance depending on the pump geometry scale were analyzed with the fixed rotational speed. These performances were expressed and evaluated as the functionalization for designing the serialized models of a single-channel pump in this work.

• 한국산학기술학회논문지
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• 제13권11호
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• pp.5587-5594
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• 2012

불포화토 역학에 있어 흐름특성에 대한 규명은 지반공학적 문제들을 해결하는데 있어 매우 중요하다. 특히, 불포화토의 흐름특성을 모사하기 위한 첫 걸음이 되는 함수특성곡선의 측정을 위해서는 측정자의 오류를 최소화할 수 있는 신뢰성있고 편리한 기법이 필수적으로 요구되어진다. 플로우 펌프 시스템을 포함하여 현재까지 많은 연구자들은 함수특성곡선을 측정할 수 있는 다양한 기법들을 개발하였다. 본 연구에서는 기존에 제안되어진 플로우 펌프시스템을 활용한 흡입력 조절 기법을 이용하여 건조과정과 습윤과정에서 정확하게 실험 공시체의 함수특성곡선을 측정하였다. 플로우 펌프 시스템을 활용한 흡입력 조절 기법을 통하여 두 가지 시료의 함수특성곡선을 산정하였으며, 실험 결과를 바탕으로 흡입력 조절 기법은 현장 조건에 맞는 조건들을 실내에서 구현할 수 있으며 또한 건조과정과 습윤과정에서 발생하는 함수특성곡선의 이력현상을 규명하는데 적절한 장비인 것을 확인하였다. 특히, 플로우 펌프시스템을 활용한 흡입력 조절 기법은 자동화된 장비와 정밀도로 인하여 높은 정확도를 이끌어낼 수 있어 측정오차를 줄임과 동시에 측정시간을 절약하여 함수특성곡선을 측정할 수 있다.

• 한국자동차공학회논문집
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• 제14권6호
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• pp.160-170
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• 2006

If hydraulic pump controlled by mechanical type regulator has more than one control function, the construction of regulator will be very complicated and control performance falls drastically. It is difficult to have more than one control function for hydraulic pump controlled by electronic type hydraulic valve due to the inconsistency of controllers. This paper proposes a multi-function control technique which controls continuously flow, pressure and power by using EPPR(Electronic Proportional Pressure Reducing) valve in swash plate type axial piston pump. Nonlinear mathematical model is developed from the continuity equation for the pressurized control volume and the torque balance for the swash plate motion. To simplify the model we make the linear state equation by differentiating the nonlinear model. A reaction spring is installed in servo cylinder to secure the stability of the control system. We analyze the stability and disturbance by using the state variable model. Finally, we review the control performances of flow, pressure and power by tests using PID controller.

• 조명전기설비학회논문지
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• 제19권6호
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• pp.92-99
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• 2005

냉동 냉장창고용 냉수펌프 시스템을 태양광발전 시스템과 연계하여 펌프의 양정 및 유량의 변화에 따른 압력의 변화에도 불구하고 목표치 압력을 일정하게 제어할 수 있도록 하였다. BLDC 모터를 벡터제어 함으로써 각 운전속도의 영역에서 최대토크 운전 및 높은 신뢰성을 가능하도록 하여 냉동 냉장창고용 냉수 펌프 시스템의 에너지 절감 효과를 실현하였다.

• 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.

• 한국화재소방학회논문지
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• 제29권2호
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• pp.33-38
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• 2015

고압과 정량 흡상을 목적으로 클리어런스가 없는 초고압 회전용적형 헬리컬기어 펌프의 개발을 진행하였다. 펌프의 내부 압력과 토출 유속을 검증하기 위해 CFD 해석을 수행하였다. 이에 따라 FVM 기법으로 유동해석을 수행하였는데 클리어런스가 없는 완전히 밀폐된 형태의 FVM 유동해석은 격자가 연속하게 구성되지 않아 유체영역이 분리되어 정상적인 결과를 얻어낼 수 없었다. 이러한 문제로 격자 구성이 필요치 않은 MPS 기법으로 유동해석을 수행하였고, MPS 유동해석을 통해 펌프의 내부 압력과 토출 유속을 확인할 수 있었다. 로터의 회전속도 1,000 rpm에서 펌프 내부의 압력은 최소일 때 19.5 bar, 최대일 때 44.6 bar이고, 평균 압력은 33.9 bar로 확인되었다. 토출 유속은 최소일 때 64.5 m/s, 최대일 때 84.8 m/s이고, 평균 유속은 76.1 m/s로 확인되었다. 본 연구를 통해 클리어런스가 없는 해석 모델의 유동해석은 FVM 기법보다는 MPS 기법이 더 적합하였음을 확인할 수 있었다. 또한 초고압 회전 용적형 헬리컬기어 펌프의 압력의 변화에 따른 유속과의 관계를 본 연구를 통해 규명할 수 있었다.

• International Journal of Fluid Machinery and Systems
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• 제7권1호
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• pp.34-41
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• 2014

Computational fluid dynamics (CFD) and particle image velocimetry (PIV) are commonly used techniques to evaluate the flow characteristics in the development stage of blood pumps. CFD technique allows rapid change to pump parameters to optimize the pump performance without having to construct a costly prototype model. These techniques are used in the construction of a bi-ventricular assist device (BVAD) which combines the functions of LVAD and RVAD in a compact unit. The BVAD construction consists of two separate chambers with similar impellers, volutes, inlet and output sections. To achieve the required flow characteristics of an average flow rate of 5 l/min and different pressure heads (left - 100mmHg and right - 20mmHg), the impellers were set at different rotating speeds. From the CFD results, a six-blade impeller design was adopted for the development of the BVAD. It was also observed that the fluid can flow smoothly through the pump with minimum shear stress and area of stagnation which are related to haemolysis and thrombosis. Based on the compatible Reynolds number the flow through the model was calculated for the left and the right pumps. As it was not possible to have both the left and right chambers in the experimental model, the left and right pumps were tested separately.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.105-106
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• 2008

As a carrier of malaria and sneak of blood, mosquitoes are an unpleasant insect. However, there are several unknown natural secretes related with mosquitoes. Among them, we focused on the blood sucking process of a female mosquito. The main objective of this study is to understand the mosquito's blood sucking mechanism that can be used to resolve the problem encountered in the injection or transport of infinitesimal biological fluids in a micro-chip. At first, the velocity fields of blood-sucking flow in a proboscis were measured using a micro-particle image velocimetry (PIV) technique. The velocity signals of flow in the proboscis show periodic variation. This seems to be resulted from the beating of the pharyngeal pump which works as driving power. To analyze the pumping mechanism, the temporal variation of the pharyngeal pump was visualized using the synchrotron X-ray micro-imaging technique. The volume variation was estimated by the help of digital image processing techniques. Once the main mechanism of blood sucking process was found, a effective micro-pumping system with high efficiency would be developed in near future.

• 대한기계학회논문집B
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• 제26권6호
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• pp.795-804
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• 2002

The optimal design code of an axial flow pump has been developed to determine geometric and fluid dynamic variables under hydrodynamic as well as mechanical design constraints. The design code includes the optimization of the complete radial distribution of the geometry by determining the coefficients of 2$^{nd}$ order polynomials to represent the three-dimensional geometry. The optimization problem has been formulated with a nonlinear multivariable objective function, maximizing the efficiency and stall margin, while minimizing the net positive suction head required. Calculation of the objective function is based on the mean streamline analysis and through-flow analysis using the present state-of-the-art model. The optimal solution is calculated using the penalty function method in which the genetic optimizer is employed. The optimized efficiency and design variables are presented in this paper as a function of non-dimensional specific speed in the range, 2$\leq$ $n_{s}$ $\leq$10. The results can be used in preliminary design of axial flow pumps.