• Nuclear Engineering and Technology
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• v.49 no.4
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• pp.801-809
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• 2017

The purpose of this study is to assess the additional neutron effective dose during passive scattering proton therapy. Monte Carlo code (Monte Carlo N-Particle 6) simulation was conducted based on a precise modeling of the National Cancer Center's proton therapy facility. A three-dimensional neutron effective dose profile of the interior of the treatment room was acquired via a computer simulation of the 217.8-MeV proton beam. Measurements were taken with a $^3He$ neutron detector to support the simulation results, which were lower than the simulation results by 16% on average. The secondary photon dose was about 0.8% of the neutron dose. The dominant neutron source was deduced based on flux calculation. The secondary neutron effective dose per proton absorbed dose ranged from $4.942{\pm}0.031mSv/Gy$ at the end of the field to $0.324{\pm}0.006mSv/Gy$ at 150 cm in axial distance.

• Solar Energy
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• v.6 no.2
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• pp.62-69
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• 1986

An analysis is made of the fully developed laminar flow and heat transfer in a parallel flat plate with heated rectangular block arrays to investigated the influence of bouyancy force. The shrouds is considered as adiabatic, while the heated block surface transmit a uniform rate of heat flux per unit axial length. The governing equations for velocity and temperature are solved by SIMPLE(Semi-Implicit Method Pressure Linked Equation) algorithm. Detailed velocity and temperature fields and overall heat transfer on wide range of Rayleigh number and various aspect ratios of heated rectangular blocks are computed. The result show that bouyancy leads to a significient enhancement in heat transfer along with a smaller increase in pressure drop, with the great enhancement found when the aspect ratio is 3.0.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.37.1-37.1
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• 2011

We report untwisting chromospheric surges of AR 10930. Hinode Solar Optical Telescope (SOT) observed AR 10930 on the west limb continuously from 11:21 UT December 18 to 09:58 UT December 19, using the Ca II H broadband filter. During the observation, rise and fall motion accompanying rotation appeared recursively. There occurred a total of 14 surges at AR 10930 over 17 hours. The average duration was 45 minutes, and the average width, and length were 8 Mm, and 39 Mm, respectively. The dynamic properties including number of turns from the rise to the fall, the axial speed and acceleration are also analyzed. We speculate that the surges occurred by recursive reconnections between the twisted prominence and large untwisted flux tube.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.179-186
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• 1999

Three-dimensional flow analysis is implemented to investigate the flow through transonic axial-flow compressor rotor(NASA R67), and to evaluate the performances of k-$\epsilon$ and Baldwin-Lomax turbulence models. A finite volume method is used for spatial discretization. And, the equations are solved implicitly in time with the use of approximate factorization. Upwind difference scheme is used for inviscid terms, but viscous terms are centrally differenced. The flux-difference-splitting of Roe is used to obtain fluxes at the cell faces. Numerical analysis is performed near peak efficiency and near stall. And, the results are compared with the experimental data for NASA R67 rotor. Blade-to-Blade Mach number distributions are compared to confirm the accuracy of the code. From the results, we conclude that k-$\epsilon$ model is better for the calculation of flow rate and efficiency than Baldwin-Lomax model. But, the predictions for Mach number and shock structure are almost same.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1005-1007
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• 2005

Small wind turbines are becoming a viable technology option to supply electricity to landowners. These systems provide energy security, product relatively no environmental harm, and in an appropriate setting can be quite cost-competitive with traditional electricity options. This paper is dealing with the methods how to overcome such inconvenience and with the analysis of characteristic and a field test with a prototype of the stand alone wind turbine was performed. The method applies to small systems, equipped with a coreless axial-flux permanent magnet(AFPM) generator in the turbine, a dc-dc converter and batteries. The analysis concentrates on the effect of the load on the power-wind speed curve of the turbine. The system is designed for direct driven, coupled with turbine and generator with a rated power of, 3kW.

• Proceedings of the KIEE Conference
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• summer
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• pp.875-877
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• 2004

Research related to renewable energy is urgently required to cope with the depletion of fossil fuel and the environmental pollution. This paper deals with maximum power control of 1kW rating wind power generator. To implement direct-drive generator, axial flux permanent magnet generator is adopted to test the converter. The blade is attached to the surface of outer rotor disk. Generally wind power generator is operated under the rated wind speed. To capture maximum power at my given wind speed, the coordination of generator and converter is essential. Buck/Boost converter is designed to charge 24V battery and under the low wind speed it operates as boost converter.

• Proceedings of the KIEE Conference
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• summer
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• pp.908-910
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• 2004

Disabled people have benefited greatly from the developments in technology over the last twenty years. Systems have been developed and refined to help them overcome, or cope with, difficulties they experience as a result of their disabilities. As technology has become cheaper, more powerful and easier to use, disabled people have taken to using them to an ever increasing degree. In this paper, we propose novel hybrid mobility devices which use a combination of human power and electric power. This paper deals with the design of a direct-drive wheel Axial-flux permanent magnet motor. This type motor prove to be the best candidate for application in electric vehicles, as in comparison with conventional motors they allow design with higher compactness, lightness. A prototype vehicle for an application as a hybrid wheelchair is designed, built, and tested.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.687-689
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• 2003

Recently, issues regarding environment and the diversification of dependence in oil are watched with keen interest. Wind power attracts most interest because of its high-energy efficiency with environment friendly functions. The paper discusses the development of a coreless axial-flux permanent magnet (AFPM) generator for a wind power system. Analyzed the Coreless AFPM generator by electromagnetic, and designed wind power generator with this. The 3 phase output of stator is rectified and fed to a common do link. The overall machine structure has high compactness and lightness, because of the lack of the iron core. The test results with a resistive load confirm the satisfactory operation of generator. Compared with conventional generator, the design has lower weight, lower Power loss and improved efficiency.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.107-109
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• 2001

The salient pole rotor type single phase SRM has a salient pole in the rotor in order to use axial direction fluxes and radial direction fluxes simultaneously. A flux linkage between the rotor and the stator are increased because of the salient pole in the rotor. But, the inductance at unaligned position and aligned position is increased together. Therefore, the length of pole are and salient pole should be selected that the inductance increment at aligned position is higher than the inductance increment at unaligned position. On this paper, we will be studied the influence of the pole arc and the salient pole length on the torque of the salient pole rotor type single phase SRM.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.30-43
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• 2021

In the 2D/1D method, a global adjoint CMFD based on the generalized equivalence theory is built to synthesize the 2D radial MOC adjoint and 1D axial NEM adjoint calculation and also to accelerate the iteration convergence of 3D whole-core adjoint transport calculation. Even more important, an advanced yet accurate two-level (TL) CMFD acceleration technique is proposed, in which an equivalent one-group adjoint CMFD is established to accelerate the multi-group adjoint CMFD and then to accelerate the 3D whole-core adjoint transport calculation efficiently. Based on these method, a new code is developed to perform 3D adjoint neutron flux calculation. Then a set of VERA and C5G7 benchmark problems are chosen to verify the capability of the 3D adjoint calculations and the effectiveness of TL CMFD acceleration. The numerical results demonstrate that acceptable accuracy of 2D/1D adjoint calculations and superior acceleration of TL CMFD are achievable.