• KIEAE Journal
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• v.12 no.1
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• pp.113-118
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• 2012

The photovoltaic is one of the most important sustainable technologies appliable to architectures. The power performance mainly depends on the installation conditions of them. This study aims to evaluate the power performance of photovoltaic system by the installation conditions, the tracking methods and reflecting mirrors. For the study, the Solar Pro computer simulations have been conducted on installation angles, solar azimuth and solar altitude. Also, the field mock-up tests are performed to of its application to verify the simulation results. Both the results of the experiment and the simulation have proved that the efficiency of 90-degree fixed angle method was higher than that of 30-degree fixed angle, the efficiency of altitude tracking was better than that of azimuth tracking method, and changing both the altitude and the azimuth together is more efficient rather than the shortened tracing way. In addition, the light-concentrating method in which the incidence angle of the sun is controlled by an adhered reflector has been analyzed to have better efficiency than the general method of tracing according to the orbit of the sun. Therefore, this thesis is expected to offer the basic data to set a more effective tracing-type of photovoltaic power generation system in the future. For this, more researches are to be conducted hereafter on a high efficiency drive motor and the establishment of an economic system.

• Bulletin of the Society of Naval Architects of Korea
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• v.8 no.1
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• pp.1-16
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• 1971

Ship hulls obtained by the streamline tracing method usually have characteristically drooped keel lines at the bottom, and a flattening of these bottoms would contribute considerably in utilizing these analytically obtainable hull forms in practical usage. In this dissertation, the author deals with a study on the determination of a practical hull form by the streamline tracing method with a particular emphasis on the bottom flattening problem. Investigations are centered around the form and the terms of bottom doublet distribution. Several examples are computed by varying bottom doublet sheet systematically while the main side source distribution is kept the same. The following conclusions are obtained based on those computed results: after the strength of a bottom doublet sheet can be determined more easily and efficiently by employing the concept of a control plane. If the distance from the distributed plane of the bottom doublet sheet to the control plane is defined as the control distance, the strength of the bottom doublet sheet, the flatness of traced lines, and the increment of the beam length ratio by adding the bottom doublet sheet are all related to the control distance by linear equations near the design bottom. It is observed that a better result can be obtained by using a "line-sampling method" for ${\zeta}_K>2T/L$, and a "plane-sampling method" for ${\zeta}_K{\leq}2T/L$, provided that the check points are sampled in the range ${\xi}{\leq}0.7$.

• The Korean Journal of Ceramics
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• v.4 no.2
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• pp.72-77
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• 1998

A defect model for UO$_2$ fuel containing soluble fission products was devised based on the defect structure of pure and doped uranias. Using the equilibrium between fuel solid-solution and fission-products and the material balance within the fuel, a tracing method to get the stoichiometry change of urania fuel with burnup was made. This tracing method was applied to high burnup urania fuel and DUPIC fuel. The oxygen potential of urania fuel turned out to increase slightly with burnup. The stoichiometry change was calculated to be negligible due to the buffering role f Mo. The oxygen potential of DUPIC fuel out to be sensitive to the initial chemical state of Mo in the fuel.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.175-178
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• 1998

Tracings streamlines in global coordinate, especially with finite element mesh, requires much computation due to C0 continuity of velocity field. In this study, a new approach is presented for the determination of streamlines from velocity field obtained by FE analysis. It is shown that amount of calculation can be drastically reduced and boundary of element can be easily treated. The approach is applied to the problem of free surface of deforming workpieces in shape rolling.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.97-99
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• 2006

Occurrence of Hwangji pond in Taebaek karst area was investigated in various hydrogeochemical ways and it is found out that there are underground cavern network and sinkholes under the pavement of Taebaek city. It is partially proved by dye tracing method.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.1
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• pp.17-22
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• 2011

In this study, a P wave emphasizing and detection algorithm from ECG signal was proposed to read arrhythmia. The algorithm uses two slope tracing waveform, the descending slope tracing wave and the ascending slope tracing wave, developed for efficient determination of slope inverting points and sudden slope changing points. The algorithm generates the slope tracing waveform which trace the original ECG wave, and subtracts one tracing wave from the other to detect P and T waves. The algorithm has been applied to MIT/BIH database in order to verify its efficacy and validity in practical applications.

• Journal of Energy Engineering
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• v.6 no.2
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• pp.119-128
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• 1997

A method to mitigate the thermal stratification flow of a horizontal pipe line is proposed by heating external bottom of the pipe with electrical heat tracing. Unsteady two dimensional model has been used to numerically investigate an effect of the external heating on the thermal stratification flow. The dimensionless governing equations are solved by using the control volume formulation and SIMPLE algorithm. Temperature distribution, streamline profile and Nusselt number distributions are analyzed under heating conditions. The numerical results of this study show that the maximum dimensionless temperature difference between hot and cold sections of the inner wall of pipe is 0.424 at dimensionless time of 1,500 and the thermal stratification phenomenon disappears at about dimensionless time of 9,000.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.164-171
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• 1999

An optimum blank design technology is required for near-net of net-shape cold forming using sheets. Originally, the backward tracing scheme has been developed for preform design in bulk forming, and applied to several forming processes successfully. Its key concept is to trace backward from the final desirable configuration to an intermediate preform of initial blocker. A program for initial blank design in sheet forming which contains the capabilities of forward loading simulation by the finite element method and backward tracing simulation, has been developed and proved the effectiveness by applying to a square cup stamping process. In the blank design of square cup stamping, the backward tracing program can produce an optimum blank configuration which forms a sound net-shape cup product without machining after forming. Another general application appears in the blank design of a cup stamping with protruding flanges, one of typical automobile components. The blank configurations derived by backward tracing simulation have been confirmed by a series of loading simulations. The approach or decision of an initial blank configuration presented in this study will be a milestone in fields of sheet forming process design.

• The Journal of the Acoustical Society of Korea
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• v.27 no.1
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• pp.1-11
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• 2008

To overcome the mid frequency limitation of geometrical acoustic techniques, the phased geometrical method was suggested by introducing the phase information into the sound propagation from the source. By virtue of phase information, the phased tracing method has a definite benefit in taking the interference phenomenon at mid frequencies into account. Still, this analysis technique has suffered from difficulties in dealing with low frequency phenomena, so called, wave nature of sound. At low frequencies, diffraction at corners, edges, and obstacles can cause errors in simulating the transfer function and the impulse response. Due to the use of real valued absorption coefficient, simulated results have shown a discrepancy with measured data. Thus, incorrect phase of the reflection characteristic of a wall should be corrected. In this work, the uniform theory of diffraction was integrated into the phased beam tracing method (PBTM) and the result was compared to the ordinary PBTM. By changing the phase of the reflection coefficient, effects of phase information were investigated. Incorporating such error compensation methods, the acoustic prediction by PBTM can be further extended to low frequency range with improved accuracy in the room acoustic field.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.12
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• pp.1110-1116
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• 2013

A 3D-ray tracing tool is a software considering reflection, penetration, and diffraction of the signals to provide accuracy. To provide communication resources effectively, communication standards adopt Heterogeneous Networks (HetNets) that includes small cells. A 3D performance evaluation methodology becomes more and more important since the coverage of the small cell networks is narrower than that of the macro cell networks. It is difficult to directly apply conventional 2D mathematical models due to the complexity of small cell network; since they have many considerations such as topography, placement of buildings and 3D beamforming techniques. In this paper, we introduce an effective performance evaluation methodology for small cell networks using 3D-ray tracing tool. From simulation results, we conclude that new performance evaluation methodologies by using 3D-ray tracing tool is more suitable than conventional methodology for small cell networks.