• 조명전기설비학회논문지
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• 제25권1호
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• pp.9-17
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• 2011

Development of high efficiency and eco-friendly LED source has been progressed continuously. Also, by nation's regulations, public institutions have changed existing luminaires to LED luminaires. However, there are several differences between existing luminaires and the intensity distribution of general planar LED luminaires. In case of changing existing luminaires to LED luminaires, by such differences, there are inefficiencies both quality aspect and energy aspect in luminous environment. Therefore, this study aims to conduct a study on the changes of intensity distribution and luminous environment by reflector shapes in indirect reflected LED luminaires with software for optical design of a luminaire (Photopia 2.0) and lighting design of a space (ReluxPro). This study shows the changes of intensity distribution and luminous environment of indirect reflected LED luminaires and indirect fluorescent lamp luminaires by reflector shapes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1459-1461
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• 1999

Distribution systems is consist of network in physical aspect, and radial in electrical aspect. Therefore, radial operation is realized by changing the status of sectionalizing switches, and is usually done for loss reduction in the system. In this paper, we propose a optimal method for distribution systems reconfiguration. Specifically, we use K-optimal algorithm and tabu search method to solve distribution systems reconfiguration for loss minimization problem.

• Journal of Welding and Joining
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• 제8권1호
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• pp.62-69
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• 1990

Being focused on the recent studies that the fatigue strength of resistance spot weldmentes can be improved by using ellipsoidal weld nuggets, the voltage and temperature distribution in resistance spot weldments were simulated for the various rectangular electrodes which had the different aspect ratio of the contact area. Because the electrode shape was not axi-symmetric, the solution domain for simulation should be three dimensional. A series of experiments were carred out to verify the analytically obtained temperature distribution in the weldment. From the calculational and experimental results, it could be revealed that the nugget took the form of ellipsoid, while both results showed a considerable discrepancy for the high aspect ratio.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.28-31
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• 2006

It is require to construct geothermal database to develop geothermal energy as renewable energy policy. It must be consist of geologic data, borehole data and geophysical data for geothermal database. In aspect of geology, there are included the distribution of geology, structural geology, geological time, rock name, density of rock, porosity, thermal diffusivity, specific capacity and thermal conductivity In order to calculate the heat general ion, it is needed to analysis the radioactivity elements as U, Th and K of rock. In aspect of borehole data, there are included temperature of depth, surface temperature and geothermal gradient And also there is geotherrnornetry using chemical components of groundwater as Na Ca, K and $SiO_2$. In aspect of geophysical data, there are some thematic map as booger gravity anomaly data and magnetic survey data and etc. In addition, it is important to descript the distribution of hot spring and water temperature.

• 한국세라믹학회지
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• 제32권6호
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• pp.653-658
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• 1995

Directional effect of applied pressure during sintering on the microstructure and fracture toughness of the heat-treated silicon nitride ceramics has been investigated. The specimens with a composition of 92Si3N4-8Y2O3(in wt%) were sintered at 172$0^{\circ}C$ by a hot press (HP ) and a hot isostatic press (HIP) and heat-treated for grain growth at 1800~20$0^{\circ}C$. The fracture toughness of the HP samples increased with the grain size while the fracture toughness of the HIP treated samples remained the same even though the grain growth occurred. This discrepancy was explained by a bimodal grain size distribution and large aspect ratio of the HPed samples and a monomodal grain size distributjion and samll aspect ratio of the HIP treated samples.

• 소성∙가공
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• 제8권3호
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• pp.295-295
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• 1999

In the present study, the corrosion behavior of AZ91D as-cast alloy was investigated form the viewpoint of the distribution aspect of precipitate ($Mg_{17}Al_{12}$) and the variation of Al concentration in the Mg-rich matrix. The dendrite arm spacing (DAS) of an as-cast specimen was measured as a function of degree which describes the distribution aspect of the precipitate, and the salt spray test was conducted for various grain-sired specimens fur 20 days. The dendrite arm spacing increased as the grain size increased to about 150㎛, but a constant value is indicated when the grain size exceeds that range. Although the relationship between the corrosion rate and grain size is of a nonlinear type, the linear trend between the corrosion rate and the dendrite arm spacing is maintained for the overall range of dendrite arm spacing. Since the precipitate in the as-cast alloy is discontinuously distributed, this linear relationship means that the variation of Al-solute concentration in the Mg-rich matrix has a more potent effect than the protective action of the precipitate on the corrosion behavior of an as-cast alloy.

• 한국농공학회논문집
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• 제55권1호
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• pp.39-48
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• 2013

The solar radiation is the primary energy source that drives many of the earth's physical and biological processes and climate change. Understanding its importance to the solar radiation observation is a key to understanding a broad range of natural processes, agricultural, energy and human activities. The purpose of this study is to estimate solar radiation using sunshine duration, and to estimate distribution of solar radiation using a topography factor considering surface slope and aspect in complex terrain. The result of regression analysis between ratio of solar radiation and sunshine duration from 2001 to 2010 shows high $R^2$ value of 0.878. Regression analyses indicated that topographic attributes including elevation, slope and aspect had significant effects on solar radiation. The variation of topographic factor with aspect and slope for the summer and winter are considered. The highest month of daily mean solar radiation at Jeju island appears in April of 20.61 $MJ{\cdot}m^{-2}{\cdot}day^{-1}$, and the lowest month appears in December of 6.90 $MJ{\cdot}m^{-2}{\cdot}day^{-1}$. These results provided useful quantitative information about the influence of topography on solar radiation in the island region.

• 한국재료학회지
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• 제30권5호
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• pp.223-230
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• 2020

As a case study on aspect ratio behavior, Kaolin, zeolite, TiO₂, pozzolan and diatomaceous earth minerals are investigated using wet milling with 0.3 mm media. The grinding process using small media of 0.3 pai is suitable for current work processing applications. Primary particles with average particle size distribution D₅₀, ~6 ㎛ are shifted to submicron size, D₅₀ ~0.6 ㎛ after grinding. Grinding of particles is characterized by various size parameters such as sphericity as geometric shape, equivalent diameter, and average particle size distribution. Herein, we systematically provide an overview of factors affecting the primary particle size reduction. Energy consumption for grinding is determined using classical grinding laws, including Rittinger's and Kick's laws. Submicron size is obtained at maximum frictional shear stress. Alterations in properties of wettability, heat resistance, thermal conductivity, and adhesion increase with increasing particle surface area. In the comparison of the aspect ratio of the submicron powder, the air heat conductivity and the total heat release amount increase 68 % and 2 times, respectively.

• 한국멀티미디어학회논문지
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• 제19권10호
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• pp.1775-1781
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• 2016

Generally, in the underwater target recognition, feature vectors are extracted from the target signal utilizing spatial information according to target shape/material characteristics. In addition, various signal processing techniques have been studied to extract feature vectors which are less sensitive to the location of the receiver. In this paper, we synthesized active echo signals using 3-dimensional highlight distribution. Then, Fractional Fourier transform was applied to echo signals to extract signal features. For the performance verification, classification experiments were performed using backpropagation and probabilistic neural network classifiers based on single aspect and multi-aspect method. As a result, we obtained a better recognition result using proposed feature extraction and multi-aspect based method.

• The Journal of Asian Finance, Economics and Business
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• 제7권10호
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• pp.491-499
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• 2020

The implementation of PPK-BLU in Indonesia was not followed by a comprehensive change in aspects of organization, human resources, and finance. Based on this background, this study aims to provide a comprehensive evaluation of the BTIP after the implementation of the PPK-BLU policy in the implementation of telecommunications services and information to the public in Indonesia. This research used integration of the McKinsey 7S method, Analytical Hierarchy Process, and Likert scale. The integration of these methods can provide a detailed quantitative analysis. Based on the overall evaluation results of carrying out the PPK BLU, BTIP has a performance value of 81.195%, which puts it within the Good category. The McKinsey 7S elements used as a whole have the following values: one aspect is categorized as Very Good, namely, the strategy aspect with a value of 91.025%; two aspects are categorized as Good (structural aspects with a value of 86.857%, and skill aspects with a value of 81.432%); three aspects are categorized as Adequate (style aspect with a value of 76.441%, staff aspect with a value of 78.605%, and share value aspect with a value of 76.331%); one aspect is categorized as Bad, that is the system aspect with a value of 67.503%.