• 한국전산유체공학회지
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• 제14권3호
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• pp.123-130
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• 2009

Hydromagnetic flow in a confined enclosure under a uniform magnetic field is studied numerically. The thermally active side walls of the enclosure are kept at hot and cold temperatures specified, while the top and bottom walls are insulated. The coupled momentum and energy equations associating with the electromagnetic retarding force as well as the buoyancy force terms are solved by an iterative procedure using the SIMPLER algorithm based on control volume approach. The changes in the flow and thermal field based on the orientation of an external magnetic field, which varies from 0 to $2{\pi}$ radians, are investigated. Resulting heat transfer characteristics are examined too.

• 대한기계학회논문집A
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• 제22권4호
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• pp.743-752
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• 1998

Numerical analysis for the flow and heat transfer in solid particle moving beds of heat exchangers is presented. The solid particle flow through the bundle of heat source tubes by the gravitational force. The heat energy is transferred through the direct contact of particles with the heat source tubes. The viscous-plastic fluid model and the convective heat transfer model are employed in the analysis. The flow field dominantly influences the total heat transfer in a heat exchanger. As the velocities of solid particles around the heat source tubes increase, the amount of heat transfer from the tubes increases. Some examples are presented to show the performance of the numerical model. The flow effect on the heat transfer is also studied through the examples.

• 한국지구과학회지
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• 제30권5호
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• pp.622-629
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• 2009

This study intended to collect data for evaluating the meteorological value of Upo Wetland which is the largest wetland in the downstream of Nakdong River. The observations were conducted in summer at the Upo Wetland and its surrounding paddy field that is the converted areas from a wetland to a paddy field. The following results are obtained: 1) The temperature of Upo Wetland area was $1^{\circ}C$ lower than the surrounding area during the day while it was a little higher during the night.; 2) The maximum wind speed in the Upo Wetland area was 3.5 m/s which is stronger than 1.6 m/s of its surrounding area. The south wind was observed in the farmland for most of the day while north winds and south winds alternated between day and night in Upo Wetland.; 3) In heat budget analysis, Upo Wetland was wasted in the form of latent heat rather than sensible heat in daytime.

• 한국초전도ㆍ저온공학회논문지
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• 제23권1호
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• pp.12-16
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• 2021

The magnetic properties of heat treated O-series high temperature superconducting (HTS) GdBCO coated conductor (CC) tapes which were formed of Ag/GdBCO/Buffer-layers/Stainless Steel (SS), were investigated by employing a Quantum Design PPMS-14. Using a modified Bean model, the critical current density J_c values have been estimated from the 𝚫m_irr(H) data, which are obtained by measuring the magnetic moment m(H) loops. For a range of intermediate fields, which are interacting or collective flux pinning area, the magnetic flux behaviors were investigated from the relationship J_c ∝ H^-β. In addition, the changes of irreversibility magnetic field H_irr line of heat-treated O-series HTS GdBCO CC tapes were analyzed, according as the annealing temperature under oxygen flowing increases. Both weak and strong break-downs were found by examining the changes of irreversibility magnetic field H_irr lines.

• 한국산업융합학회 논문집
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• 제5권2호
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• pp.133-139
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• 2002

In this paper, the magneto-thermal analysis of an induction heating jar is presented as an efficient design. The magnetic field inside the axisymmetric shaped cooker is analyzed using an axisymmetric FEM(Finite Element Method) and the effectual heat source is obtained by calculation of the induction current in the Jar. The temperature distribution can be calculated using the heat source and heat equation.

• 대한설비공학회지:설비저널
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• 제12권4호
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• pp.219-226
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• 1983

Cyclic heating performance of 3 ton air-to-air unitary heat pump installed in a residence in the Washington, D.C. area was determined by applying the bin method to field test result. Cyclic degradation coefficient Cn of heat pump may be expressed in terms of heating load factor HLF as the following : $$C_D=\frac{1-HLF^m}{1-HLF}$$ where $$C_D{\ge}m$$ The less is the value of exponent m, the better is, the performance of a heat pump, depending upon the heat pump design.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2004년도 학술.기술논문발표회
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• pp.11-14
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• 2004

In this paper, field application of mass concrete using setting time difference of super retarding agent is reported to reduce hydration heat of concrete placed at newly constructed apartment house in Busan. Horizontal placing lift is applied. According to test results. slump and air content meets the requirement of target values. For compressive strength, it exceeds the nominal strength ordered by the costumer. Compressive strength of concrete cured in place is achieved more than the values of nominal strength at l4days. For temperature history, maximum temperature of center at top section shows 58.5$^{\circ}C$, and at bottom section, 62.6$^{\circ}C$. According to naked eye's investigation, no hydration heat crack is observed at the surface of concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2005년도 춘계 학술기술논문발표대회 논문집
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• pp.21-24
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• 2005

In this paper, field application of mass concrete using setting time difference of super retarding agent is reported to reduce hydration heat of concrete placed at newly constructed apartment house in Daejeon. Horizontal placing lift is applied. According to test results,: slump and air content meets the requirement of target values. For compressive strength, it exceeds the nominal strength ordered by the costumer. For temperature history, maximum temperature of center at top section shows $25.6^{\circ}C$, and at bottom section, $35.4^{\circ}C$. According to naked eye's investigation, no hydration heat crack is observed at the surface of concrete.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.653-655
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• 1992

Longitudinal and transverse normal zone propagation in the superconducting coil are analyzed and propagation velocity is derived from the heat balance equations in the propagating boundary region. Transverse velocity is nearly $10^{-2}$ order of longitudinal velocity. Propagation velocity ie linearly proportional to the transport current. Increasing lamp current speeds up longitudinal velocity by 0.279 m/s under the applied field of 2T. Transient heat transfer has a significant effect on normal zone propagation velocity and it decreases longitudinal velocity by 4.2 m/s under the applied field of 2T as being compared to steady-state heat transfer.

• Steel and Composite Structures
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• 제24권3호
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• pp.359-367
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• 2017

In this work, transient heat transfer analysis of functionally graded (FG) carbon nanotube reinforced nanocomposite (CNTRC) cylinders with various essential and natural boundary conditions is investigated by a mesh-free method. The cylinders are subjected to thermal flux, convection environments and constant temperature faces. The material properties of the nanocomposite are estimated by an extended micro mechanical model in volume fraction form. The distribution of carbon nanotube (CNT) has a linear variation along the radial direction of axisymmetric cylinder. In the mesh-free analysis, moving least squares shape functions are used for approximation of temperature field in the weak form of heat transform equation and the transformation method is used for the imposition of essential boundary conditions. Newmark method is applied for solution time depended problem. The effects of CNT distribution pattern and volume fraction, cylinder thickness and boundary conditions are investigated on the transient temperature field of the nanocomposite cylinders.