• Journal of Information Display
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• v.7 no.4
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• pp.1-4
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• 2006

The optical performances of rounded prism films were investigated using a ray tracing technique. The angular distribution of the luminous intensity was obtained as functions of the prism pitch and the curvature of rounded apex and valley of prism arrays. The gain of the on-axis luminance decreased with decreasing curvature (increasing diameter) and pitch. The existence of the curved area on the prism film decreased the recycling efficiency of the prism film, i.e., the rays which would otherwise have been recycled through total internal reflections via the prism surfaces were refracted on the curved regions and redirected toward directions other than the on-axis direction. Quantitative correlation between the luminance gain and the curvature in addition to the prism pitch was obtained, which might serve as basic data for the optimization of prism films and the manufacturing processes.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.12
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• pp.60-66
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• 2011

There are several technological problems have to be resolved for LEDs to be used as a general purpose light source. In addition, there are several differences between existing luminaires and the general planer LED luminaire for the intensity distribution. Therefore, the optical engineer then faces the challenging a problem of designing for a spatially extended and non-uniform light source. In the previous studies on the optical design of luminaires, a lot of studies on reflectors and light source have been conducted but the ones on prisms and lenses are insufficient at present. This study developed the numerical model of planar prism LED luminaire to control luminous intensity distribution of LED luminaires. And this study presents an optical calculation process for the prism optical design of a planar prism LED luminaire and a comparison of the simulation results between the developed numerical model and Photopia 2.0 to verify the accuracy of the numerical model. In addition, this study showed a method for the control of various luminous intensity distribution from the developed numerical model.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.11
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• pp.1496-1508
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• 1997

The effects of porous wind fence on the pressure characteristics around a 2-dimensional prism model of triangular cross-section were investigated experimentally. The fence and prism model were embedded in a neutral atmospheric surface boundary layer over the city suburb. In this study, various fences of different porosity, back fence, inclination angle of prism and location of additional back prisms were tested to investigate their effects on the pressure and wall shear stress of the prism surface. The fence and prism had the same height of 40 mm and Reynolds number based on the model height was Re=3.9*10$^{4}$. The porous fence with porosity 40% was found to be the best wind fence for decreasing the mean and pressure fluctuations on the prism surface. By installing the fence of porosity 40%, the wall shear stress on the windward surface of prism was largely decreased up to 1/3 of that without the fence. This indicates that the porous fence is most effective to abate the wind erosion. Pressure fluctuations on the model surface were decreased more than half when a back fence was located behind the prism in addition to the front fence. With locating several back prisms and decreasing the inclination angle of triangular prism, the pressure fluctuations on the model surface were increased on the contrary.

• Journal of Elementary Mathematics Education in Korea
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• v.20 no.3
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• pp.393-406
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• 2016

In the sixth grade mathematics, drawing of development figures of the triangular prism and the quadrangular prism is recommended in terms of the creativity. In this sense, the teacher has the need to check in advance all the possible development figures of the triangular prism and the quadrangular prism before teaching on them. However, previous studies that currently give all the possible development figures of the triangular prism and the quadrangular prism are hard to find. For this reason, in this paper, as a study of teaching materials for the professional development of elementary school teachers, the method of finding all the possible development figures of the triangular prism and all the possible development figures of the quadrangular prism without omissions and overlaps and the number of each of development figures which can be obtained by that method are discussed. Here lengths of the three sides of base planes of the triangular prism are different each other and lengths of the four sides of base planes of the quadrangular prism are different each other. This discussion is needed in terms of a study of teaching materials in order to prepare for predictable questions to ask the number of the possible development figures of the triangular prism and the number of the possible development figures of the quadrangular prism in classes. In addition, through this discussion, this paper presents the development figures of the triangular prism and the development figures of the quadrangular prism without omissions and overlaps. And teachers can take advantage of them for determining the correctness of the development figures drew by students and guiding students to draw the development figures creatively in actual classes.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.2
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• pp.27-46
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• 2016

In this study, the parameter-elevation regressions on independent slopes model-Kongju National University(PRISM-KNU) system was developed to interpolate monthly precipitation data. One of the features of PRISM-KNU is that it can adjust the allowable range of slope according to the elevation range in the equation representing a linear relationship between the precipitation and elevation. The parameter value of the model was determined by using the optimization technique, and the result was applied to produce monthly precipitation data with a spatial resolution of $1{\times}1km$ from 2000 to 2014 in South Korea. In the result, the Kling-Gupta Efficiency for model evaluation was over 0.7 in 86% of the total cases simulated. In addition, a dramatic change in the spatial pattern of precipitation data was observed in the output of the Modified Korean PRISM, but such a phenomenon did not occur in the output of the PRISM-KNU. This study confirmed the appropriateness of the PRISM-KNU, and the result showed that the spatial consistency of the data produced by the model improved compared with that produced by the Modified Korean PRISM. It is expected that the PRISM-KNU and its output will be utilized in various studies in the future.

• Education of Primary School Mathematics
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• v.25 no.1
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• pp.1-17
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• 2022

It summarized and analyzed how the definitions of prism, which is the main mathematics education contents of the upper grades of elementary school, have changed from the teaching period to the 2015 revised curriculum. To this end, the definition method was divided into three methods, and how each method was used in each curriculum was examined. Through this, it was confirmed that the definitions of prism were quite different for each curriculum period. In addition, the implications for the definition of each prism were compressed and presented. It will be an opportunity for the textbook author to think about what is a more meaningful definition method of prism.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.3
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• pp.36-51
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• 2012

The demand for a climatological dataset with a regular spaced grid is increasing in diverse fields such as ecological and hydrological modeling as well as regional climate impact studies. PRISM(Precipitation-Elevation Regressions on Independent Slopes Model) is a useful method to estimate high-altitude precipitation. However, it is not well discussed over the optimization of PRISM parameters and DEM(Digital Elevation Model) resolution in South Korea. This study developed the PRISM and then optimized parameters of the model and DEM resolution for producing a gridded annual average precipitation data of South Korea with 1km spatial resolution during the period 2000-2005. SCE-UA (Shuffled Complex Evolution-University of Arizona) method employed for the optimization. In addition, sensitivity analysis investigates the change in the model output with respect to the parameter and the DEM spatial resolution variations. The study result shows that maximum radius within which station search will be conducted is 67km. Minimum radius within which all stations are included is 31km. Minimum number of stations required for cell precipitation and elevation regression calculation is four. Optimizing DEM resolution is $1{\times}1km$. This study also shows that the PRISM output very sensitive to DEM spatial resolution variations. This study contributes to improving the accuracy of PRISM technique as it applies to South Korea.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.15-18
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• 2009

Photopia, LightTools, and ASAP are typical software for optical design of a luminaire. Through using various lighting simulation software some different results can be found under the same conditions. Therefore, the purpose of this paper is to compare simulated photometric data and values illuminance of different types of LED prism luminaires under the same conditions. Then, LED prism luminaires were divided into the linear type and the planar type. Also three kinds of prism angles were divided into $30^{\circ}$, $45^{\circ}$, and $60^{\circ}$. In addition, the reasons for such differences were analyzed.

• Clinical and Experimental Pediatrics
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• v.51 no.11
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• pp.1158-1164
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• 2008

Purpose : To investigate the discriminative ability of pediatric index of mortality 2 (PIM2) and pediatric risk of mortality III (PRISM III) in predicting mortality in children admitted into the intensive care unit (ICU). Methods : We retrospectively analyzed variables of PIM2 and PRISM III based on medical records with children cared for in a single hospital ICU from January 2003 to December 2007. Exclusions were children who died within 2 h of admission into ICU or hopeless discharge. We used Students t test and ANOVA for general characteristics and for correlation between survivors and non-survivors for variables of PIM2 and PRISM III. In addition, we performed multiple logistic regression analysis for Hosmer-Lemeshow goodness-of-fit, receiver operating characteristic curve (ROC) for discrimination, and calculated standardized mortality ratio (SMR) for estimation of prediction. Results : We collected 193 medical records but analyzed 190 events because three children died within 2 h of ICU admission. The variables of PIM2 correlated with survival, except for the presence of post-procedure and low risk. In PRISM III, there was a significant correlation for cardiovascular/neurologic signs, arterial blood gas analysis but not for biochemical and hematologic data. Discriminatory performance by ROC showed an area under the curve 0.858 (95% confidence interval; 0.779-0.938) for PIM2, 0.798 (95% CI; 0.686-0.891) for PRISM III, respectively. Further, SMR was calculated approximately as 1 for the 2 systems, and multiple logistic regression analysis showed ${\chi}^2(13)=14.986$, P=0.308 for PIM2, ${\chi}^2(13)=12.899$, P=0.456 for PRISM III in Hosmer-Lemeshow goodness-of-fit. However, PIM2 was significant for PRISM III in the likelihood ratio test (${\chi}^2(4)=55.3$, P<0.01). Conclusion : We identified two acceptable scoring systems (PRISM III, PIM2) for the prediction of mortality in children admitted into the ICU. PIM2 was more accurate and had a better fit than PRISM III on the model tested.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.3
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• pp.223-233
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• 1999

The wind-flow characteristics over a two-dimensional triangular prism with a porous windbreak are numerically investigated. The geometry is a simplified model of large outdoor stack with a frontal wall-type windbreak which is used to prevent particle dispersion by reducing wind speed over stak surface. In the present numerical model, the RNG k-$\varepsilon$ model, the orthogonal grid system and the QUICK scheme are employed for the successful simulation of separated flow. The predicted results are compared and validated with the associated wind-tunnel experiments. In addition, the trajectories of dispersed particles and their sedimentation characteristics are quantitatively investingated using a Lagrangian turbulent-dispersion model.