• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.1
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• pp.1-8
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• 2009

The simulation of a heat pump dryer has been carried out to figure out the effect of air flow rate on the drying performance represented by MER, SMER, and so on. The simulation includes the analyses of one-stage heat pump cycle and simple drying process using the drying efficiency. The heat pump cycle with Refrigerant 134a has been considered. In the dryer, some of drying air from the drying chamber flows through the heat pump system, the rest of air bypasses the heat pump system. The two air flows joins before the drying chamber inlet. The performance parameters considered in the present study are MER, SMER, the temperature and humidity of drying air. Those parameters are compared for different total air flow rate or bypass air flow rate.

• Journal of Biomedical Engineering Research
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• v.8 no.2
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• pp.161-170
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• 1987

A new type of motor-driven total artificial heart system with a rolloing-cylinder mechanism has been developed. The prototype system consists of a brushless DC motor inside of a rolling-cylinder, two arc shaped pusher-plate s, and two ventricles of smooth, seamless polyurethane sacs. The motor-driven pump has the advantages of being portable and quiet compared to the present air-driven pump. It can also be controlled more accurately. This rolling-cylinder type electromechanical pump has several structural advantages including small size and weight, as compared to other research groups' motor-driven pumps. The results of mock circulation tests confirm sufficient pump output capacity(cardiac output . 9 L/min, at aortic pressure'120mmHg, with heart rate . 120 BPM) for animal implantation of our prototype system.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.419-424
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• 2002

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. A flow simulation facility is being developed for the endurance test of reactivity control units for extended life times and the verification of structural integrity of those experimental facilities prior to loading in the HANARO. This test facility is composed of three major parts; a half-core structure assembly, flow circulation system and support system. The flow circulation system is composed of a circulation pump, a core flow pipe, a core bypass flow pipe and instruments. The system is to be filled with de-mineralized water and the flow should be met the design flow to simulate similar flow characteristics in the core channel of the half-core test facility to the HANARO. This paper, therefore, describes an analytical analysis to study the flow behavior of the system. The computational flow analysis has been performed for the verification of system pressure variation through the three-dimensional analysis program with standard k-$\epsilon$ turbulence model and for the verification of the structural piping integrity through the finite element method. The results of the analysis are satisfied the design requirements and structural piping integrity of flow circulation system.

• The KSFM Journal of Fluid Machinery
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• v.7 no.1 s.22
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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.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.772-777
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• 1997

Previous MELCOR and SCDAP/RELAP5 nodalizations for simulating the counter-current, natural circulation behavior of vapor flow within the RCS hot legs and SG U-tubes when core damage progress can not be applied to the steady state and water-filled conditions during the initial period of accident progression because of the artificially high loss coefficients in the hot legs and SG U-tubes which were chosen from results of COMMIX calculation and the Westinghouse natural circulation experiments in a 1/7-scale facility for simulating steam natural circulation behavior in the vessel and in the hot leg and SG during the TMLB' scenrio. The objective of this study is to develop a natural circulation modeling which can be used both for the liquid flow condition at steady state and for the vapor flow condition at the later period of in-vessel core damage. For this, the drag forces resulting from the momentum exchange effects between the two vapor streams in the hot leg was modeled as a pressure drop by pump model. This hot leg natural circulation modeling of MELCOR was able to reproduce similar mass flow rates with those predicted by previous models.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.434-437
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• 1999

An EM pump is used for the purpose of transporting the electrically conducting liquid sodium of the high temperature that is used as a coolant in the liquid metal reactor. In the present study, the pilot pump has been designed and manufactured for the high temperature of $600^{\circ}C$ by the equivalent circuit materials and the consideration of the materials and functions. The length and diameter of the pump are given as 84 cm and 10 cm each due to the fixed geometry of the circulation system to be installed. The characteristic of the developing pressure and efficiency is found out by using Laithewaite\`s standard design formula. It is shown that the developing pressure and efficiency are maximized at the frequency of 15 Hz from the curve. The annular channel gap of 3.95 mm is selected in the range of the reasonable hydraulic frictional loss. The components of the pump consist of the material for the high temperature. And then, the pump is manufactured to have the nominal flowrate of 40 1/min and developing Pressure of 1.3 bar.

• Journal of Chest Surgery
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• v.44 no.5
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• pp.323-331
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• 2011

Background: Myocardial revascularization in patients with renal insufficiency is challenging to the cardiac surgeon, irrespective of utilizing extracorporeal circulation. This study aimed to compare the number of bypass grafts and the mid-term results and to evaluate independent survival predictors in patients with renal insufficiency undergoing on-pump or off-pump myocardial revascularization. Materials and Methods: We retrospectively analyzed the data of 103 patients with renal insufficiency, who had isolated myocardial revascularization between January 1999 and January 2009. The patients were divided into two groups, the on-pump group and the off-pump group. Results: The off-pump group received a significantly greater number of distal arterial grafts than the on-pump group. However, the mean number of total grafts, the degree of complete revascularization, and survival rate of the patients were not significantly different between the two groups. Multivariate analysis showed the independent predictors for reduced mid-term survival were the number of total grafts and postoperative periodic renal replacement therapy. Off-pump myocardial revascularization does not decrease the number of bypass grafts or influence on the mid-term results for patients with renal insufficiency, compared to on-pump myocardial revascularization. Conclusion: Myocardial revascularization with a large number of total grafts has a beneficial effect on survival in patients with renal insufficiency, irrespective of utilizing extracorporeal bypass.

• Solar Energy
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• v.6 no.1
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• pp.24-30
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• 1986

A concentrating solar collector of parabolic-cylindrical type is designed and constructed to provide a heat source of higher temperature for drying processes. Usually collectors of concentrating type require such peripheral auxiliary units as solar tracking system, heat medium circulation pump and temperature controller. However in this study, for simplification's sake in the maintenance of a collector system, it is intended to design a concentrating collector system which does not furnish these auxiliary units by adapting natural circulation system instead of foced circulation and by adjusting collector system to solar altitude manually and periodically. And based on the experimental data, a conceptual design for a heat sources of 50KWt thermal output is presented and discussed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.852-858
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• 2010

In an absorption chiller, solution is circulated by a solution pump with an inverter to vary flow rate depending on operating conditions. For optimal operation, the solution level in the high temperature generator should be kept constant. However, a sensor for measuring continuous level is not available because of varying solution concentration. Instead, level switches are used and hence feedforward control associated with limit checking is a common practice. In the study, inverter frequencies are estimated from a dynamic simulation model and pump performance. Designed frequencies are compared with those implemented in real chillers. It was found that the frequencies used in real chillers are larger than those needed in circulation flow rates. It was intended to prevent system shut-off caused by dry-out. However, it is necessary to minimize the excessive frequency setting in order to reduce frequent pump stops and the range of solution level for continuous pump operation.

• Proceedings of the KIEE Conference
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• 1999.11a
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• pp.1-3
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• 1999

EM (ElectroMagnetic) pump is used for the purpose of transporting liquid sodium coolant with electrical conductivity in the LMR(Liquid Metal Reactor). (In the present study, pilot EM pump has been designed by using of equivalent circuit method which is commonly employed to analyze linear induction machines for the test of removal of residual heat. The length and diameter of the pump have fixed values of 840 mm and 101.6 mm each by taking account of geometrical size of circulation loop for the installation of EM pump. Flowrate versus developing pressure is related from Laithwaite's standard design formula and the characteristic analyses of developing force and efficiency are carried out according to change of input frequency. From the characteristic curve, input frequency of 13 Hz is determined as the design frequency. On the other hand, The annular air gap size of 6.05 mm is selected not to bring about too much hydraulic loss. Resultantly design analysis makes pump have the electrical input of 604 VA and the hydrodynamical capacity of 1.3 bars and 40 l/min.