• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.102-115
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• 2020

In this study, the SST k - ω turbulence model and the sliding mesh technology based on RANS method have been adopted to simulate the exciting force and hydrodynamic of a pump-jet propulsor in different oblique inflow angle (0°, 10°, 20°, 30°) and different advance ratio (J = 0.95, J = 1.18, J = 1.58).The fully structured grid and full channel model have been adopted to improved computational accuracy. The classical skewed marine propeller E779A with different advance ratio was carried out to verify the accuracy of the numerical simulation method. The grid independence was verified. The time-domain data of pump-jet propulsor exciting force including bearing force and fluctuating pressure in different working conditions was monitored, and then which was converted to frequency domain data by fast Fourier transform (FFT). The variation laws of bearing force and fluctuating pressure in different advance ratio and different oblique flow angle has been presented. The influence of the peak of pulsation pressure in different oblique flow angle and different advance ratio has been presented. The results show that the exciting force increases with the increase of the advance ratio, the closer which is to the rotor domain and the closer to the blades tip, the greater the variation of the pulsating pressure. At the same time, the exciting force decrease with the oblique flow angle increases. And the vertical and transverse forces will change more obviously, which is the main cause of the exciting force. In addition, the pressure distribution and the velocity distribution of rotor blades tip in different oblique flow angles has been investigated.

• Journal of Power System Engineering
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• v.3 no.4
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• pp.28-35
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• 1999

An application of scroll compressor to the residential air conditioning and heat pump markets has generated many reliability problem, especially abnormal noise. Most of these noise problems is due to the check valve and compliance between FS(Fixed Scroll) and OS(Orbiting Scroll). FS and OS are the main parts of scroll compressor and are the main pumping part. But check valve has the role of protection of reverse rotation of OS when power is off. Check valve have several noise problems. Among them, shut down noise and valve movement noise is more than severe than any other problem. In this paper covers with these two noise problem.

• Journal of Chest Surgery
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• v.44 no.4
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• pp.288-291
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• 2011

Postoperative coronary arterial spasm is a rare but potentially fatal complication. A 51-year-old male patient with a history of a reactive ergonovine stress test coronary angiogram developed refractory coronary artery spasm after undergoing minimally invasive direct coronary artery bypass grafting of the left anterior descending coronary artery. The patient was successfully managed with rapid implementation of intra-aortic balloon-pump counter pulsation and extracorporeal membrane oxygenation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.196-202
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• 1997

A reinforced hydraulic hoses,caiied a resonator hoses,with fixible metal tube are commonly used in automotive power steering hydraulic systems to attenuate and eliminate the objectionable fluid borne noise(pressure ripple) or vibration produced by a pump or steering gear. To achieve better nose attenuation in automotile vehicles, the investigations on propagation and attenuation characteristics of fluid borne pressure ripple in power steering hydraulic ciruit are required. So, this paper descibes a mathematical model of hydraulic hoses to support design the power steering hydraulic circuit and analyze the attenuation characteristics of flow and pressure ripples. The model is based on the transfer matrix approach. The experimental results show that the pulsation attenuation characteristics of hydraulic house is remarkably affected by the flexible metal tube inserted coaxially inside a hydraulic hose with a finite length as well as viscoelastic properties of house wall. It is also shown that the predicted results bymodel proposed here agree well with the measured results over a wide frequency range. These results will assist in the modeling and design of hydraulic hoses, and hear, should provide a means for designing a quieter automotive power steering hydraulic systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.652-657
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• 2000

In this paper, Firstly, it is shown that the high vibration source of piping system is the pulsation transmission of pipe line element, such as, orifice plate, valves and the control valve is a broad band source and the branch wall and the cavity have vortex frequency. Secondly, in order to decrese the high vibration of piping system, some practical Friction damper with high damping have been developed and its effectiveness is investigated as installing it at piping system practically.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.907-910
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• 2012

Since the inner barrel assembly of the Advanced Power Reactor 1400 reactor vessel is a new design feature introduced instead of CEA(control element assembly) shroud assembly, the inner barrel assembly can be a significant object of structural integrity assessment. This paper covers the structural responses of top plate, which is a component of the inner barrel assembly, against the deterministic hydraulic load induced by pump pulsation and the random hydraulic load induced by turbulence of coolant. The top plate responds to the deterministic hydraulic load more than to the random hydraulic load and shows enough structural integrity. The results of this paper will be important basis for the selection of instruments and measurement location.

• Journal of Power Electronics
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• v.6 no.1
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• pp.29-37
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• 2006

A sensorless control for an IPM (Interior Permanent Magnet) synchronous motor in a single piston rotary compressor is presented in this study. The rotor position is estimated from the d-axis and q-axis current errors between the real system and a motor model of the position estimator. The torque pulsation of the single piston rotary compressor is compensated to reduce speed ripples, as well as, mechanical noise and vibration. The proposed sensorless drive enables the compressor to operate at a lower speed which increases energy savings and reduces mechanical noise. It also gives high speed operations by a flux weakening control for rapid air-cooling and heating of the heat pump air-conditioners.

• Journal of Biomedical Engineering Research
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• v.38 no.4
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• pp.168-174
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• 2017

To improve and downsize the KIOM-Pulse Analysis System(KIOM-PAS), which has been traditionally used in clinical trials, a miniaturized PAS(M-PAS) with a pneumatic pump has been developed. M-PAS is composed of a measurement module and an arm-mounting module, on which an arm can be placed. The measurement module is equipped with a pressing component and sensor, which is a wearable wristband. The arm-mounting module includes a pneumatic motor, data acquisition board and valves. In addition, the measurement module is divided into a fixing module of band type for attachment to a pulsation site and a sensing module, which includes a sensor and a tube. The fixing module and sensing module are constructed independently, and the detachable fastening method improves the posture convenience of the subject during measurement. M-PAS has been reduced to 1/6 the size of KIOM-PAS, and the measurement time is shortened by 22%. Using a simulator, the difference between the waveforms measured by the two devices exhibited a high degree of similarity of within 3.65%. M-PAS represents improvements in size and convenience compared with KIOM-PAS, and it is expected to be widely used in clinics in the future because it improves the attachment method of the fixing module.

• Journal of Chest Surgery
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• v.3 no.1
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• pp.47-54
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• 1970

This is a report on two cases of aortic prostheses using Nylon tube. (Edwards-Tapp A-G Tube, Chemically treated braided Nylon arterial grafts). Especially, the complications after infection of synthetic graft are discussed with reviewing literature. First case was the patient who came to our hospital with rupture of the right femoral artery at the femoral fossa due to pyogenic necrotic process. After femoral arterial prostheses, good pulsation of dorsal artery of foot was obtained. However, the tube was obstructed after 8 weeks postoperatively due tll the complication of infection. In spite of the tube was removed because of obstruction and foreign body reaction of synthetic graft, an amputation of the leg was not necessary for formation of good collateral circulation. Second case was a case of aortic aneurysmal rupture in thoraco-abdominal junction which developed by the trauma of rib resection for osteomyelitis of the left 12th. rib An implantation of aortic graft was performed at the lowest tho13cic aorta by the way of thoraco-abdominal bypass without arterial pump. However, infection produced pyothorax in the left pleural cavity, exposing the tube within the pyothorax. The rupture of the anastomosed upper line occurred in 8 weeks postoperatively and the patient expired.

• Nuclear Engineering and Technology
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• v.51 no.6
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• pp.1658-1668
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• 2019

Nuclear power generates a large portion of the energy used today and plays an important role in energy development. To ensure safe nuclear power generation, it is essential to conduct an accurate analysis of reactor structural integrity. Accordingly, in this study, a methodology for obtaining accurate structural responses to the combined seismic and reactor coolant loads existing prior to the shutdown of a nuclear reactor is proposed. By applying the proposed analysis method to the reactor vessel internals, it is possible to derive the seismic responses considering the influence of the hydraulic loads present during operation for the first time. The validity of the proposed methodology is confirmed in this research by using the finite element method to conduct seismic and hydraulic load analyses of the advanced APR1400 1400 MWe power reactor, one of the commercial reactors. The structural responses to the combined applied loads are obtained using displacement-based and stress-based superposition methods. The safety of the subject nuclear reactor is then confirmed by analyzing the design margin according to the American Society for Mechanical Engineers (ASME) evaluation criteria, demonstrating the promise of the proposed analysis method.