• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.8
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• pp.1257-1261
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• 1989

The propagation of electromagnetic waves in a photorefractive crystal is considered. The electromagnetic waves(i.e. TE waves and TM, waves) incident upon the crystal at any incident angle are coupled with reflected waves due to the Fresnel's reflectance in the photorefractive crystal. This coupling leads to a nonreciprocal optical transmissivity. About some incident angles, the optical transmissivity of TE and TM waves in regard to the coupling strength is investigated.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1193-1198
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• 2003

Translucent plastics are commonly used in packaging of mechanical and/or electrical components. Although Rapid Prototyping(RP) provides prototypes of various materials, translucent RP parts are not readily available from most RP processes. ABSi is one of the ABS materials available for Stratasys' FDM process, and the material has potential to be translucent. In this paper, two post-processing techniques were applied in order to increase optical transmissivity of the parts made of FDM's ABSi. First, elevated temperature condition was applied resulting in increased transmissivity while dimensional shrinkage was observed. Second, resin infiltration and surface sanding provided upto 16% transmissivity without shrinkage. These post-processes can be selectively applied to increase transmissivity of ABSi parts. Thus, translucent FDM part can be fabricated from regular FDM process followed by the post-processes developed in this study.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.9
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• pp.1524-1530
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• 2003

Translucent plastics are commonly used in packaging of mechanical and/or electrical components. Although Rapid Prototyping(RP) provides prototypes of various materials, translucent RP parts are not readily available from most RP processes. ABSi is one of the ABS materials available for Stratasys' FDM process, and the material had potential to be translucent. In this paper, two post-processing techniques were applied in order to increase optical transmissivity of the parts made of FDM's ABSi. First, elevated temperature condition was applied resulting in increased transmissivity while dimensional shrinkage was observed. Second, resin infiltration and surface sanding provided up tp 16 ％ transmissivity without shrinkage. These post-processes can be selectively applied to increase transmissivity of ABSi parts. Thus, translucent FDM part can be fabricated from regular FDM process followed by the post-processes developed in this study.

• Journal of Environmental Science International
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• v.4 no.1
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• pp.13-18
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• 1995

In order to examine the effect on the insolation of cloud cover, we analyzed the data of the insolation, cloud cover and surface air pressure in Pusan during the period of 1991. 10 - 1993.1. At first, we investigate the atmospheric transmissivity A(t) using the Beer's law at clear skies. The atmospheric transmissivity is characterized by cold season high and warn season low. From this atmospheric transmissivity, the empirical formula that shows the variation of the insolation due to the cloud cover is obtained. The result formula is I : l0 A(tn)·( 0.7-0.05×m ). 1 is the insolation that reaches the surface when cloud cover is m and to is solar constant. Although the result is some rough it seems meaningful that the estimation of insolation can be made only from the routine data.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.2
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• pp.336-343
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• 2009

Because ships are very isolated and independent objects when sailing on the ocean, if a fire and smoke occurs, nobody can be sure to escape safely from ship at the moment. On the focus of the relationship between the sight transmissivity by fire smoke density and the life safety, this study performs simulations and experiments, respectively. To evaluate the theoretical evacuation time, CFAST software which is known as a 2 zone model analysis tool is used, and the result is 54 seconds from ECR(Engine Control Room) exit to upper deck exit and 34 seconds from bosun store to upper deck exit. And totally 12 types of experiments are performed with other 10 persons per experiment. As the result, it is cleared that the low sight transmissivity leads to the low life safety and the obstruction which can be happen unexpectedly on the evacuation way on fire makes it worse. At the condition of the smoke density 0%, over 90% people arrive at upper deck exit safely. But with the transmissivity of 8%, 70%(from ECR) and 30%(from bosun store) among experiment persons of each can survive, and with same density and unexpected obstruction, the survival ratio goes down to only 20% and 10%.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.4
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• pp.125-136
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• 1996

In order to investigate the characteristics of gravity drainage for geotextile, small-scale model tests for the geotextile chimney drain of earth dam which is a typical type of gravity drainage were carried out using 15 kinds of nonwoven and composite geotextiles. According to the results of this study, the drainage discharge of geotexgile drain generally increases with exponential function as hydraulic head increases and the increasing rate is greater in the coarser soil of dam material. It has a trend to increase when the construction slope of geotextile drain is steeper and the number of layers of geotextile is more. The relationship between the transmissivity of geotextile and the drainage discharge has positive correlation and the rate of increase is greater in the coarser soil. The geotextile products must be carefully selected in consideration of transmissivity of geotextile when the soil to be drained is coarser and the seepage flow is relatively high. Most of staple fiber nonwoven geotextile used in this study are found to be appropriate for drainage purpose. Among them, the composite geotextile the type of which geotextile is evaluated to be the most excellent material. But the geotextile of low permeability such as filament thermal bonded and filament spunbonded nowovens closely examined their transmissivity especially to be used for drainage function.

• Korean Journal of Metals and Materials
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• v.46 no.6
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• pp.377-381
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• 2008

Prism sheet of LCD BLU which depends on supply from Japan and U.S.A was studied by using Si anisotropic etching and injection molding technologies. First, the prism sheet was patterned on Si wafer through photolithography, and the best conditions of Si etching were determined through etching Si wafer with TMAH to obtain straight optimized zigzag patterns, and a cross pattern to provide light diffusion and concurrent focusing. The etch rate of TMAH was concluded to be constant for $25wt%-70^{\circ}C$ condition. Ni stamp of prism sheet was made by electrodeposition using patterned Si wafer, normal or fast H/C(Heating/Cooling) injections were carried out to fabricate prism sheet. It was known that fast H/C injection could fabricate prism sheet more accurately than normal injection. Zigzag patterns and the cross pattern showed higher transmissivity than the straight patterns because of light diffusion through diagonal direction. The fast H/C injection for zigzag patterns showed lower transmissivity than normal injection because there occurred more light diffusion through precise injection patterns, but the fast H/C injection for straight patterns showed only refraction without diffusion, causing lower transmissivity than normal injection.

• Journal of Bio-Environment Control
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• v.7 no.4
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• pp.290-297
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• 1998

In this study an optimization of greenhouse roof shape was performed to maximize solar light transmission which is one of the most important elements in greenhouse environment. To determine roof shape that maximize the total light transmissivity, a computer model for analysing light transmissivity was composed and the Genetic Algorithms was applied for solving optimization problems. By setting composite model as objective function(fitness function), the optimum combination of design variables(roof inclination angle, width ratio) was searched using Genetic Algorithms. The optimum combination of input variables for the maximum light transmissivity at Suwon in winter was found 40 degree root angle , 0.5 width ratio, for two span greenhouses and 37 $_。 / roof angle, 0.7 width ratio, for single span greenhouses.es.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.52-52
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• 1995

The temporal and spatial distribution of atmospheric transmissivity and depletion rate of solar radiation are investigated, and are compared to the concentration of several components of air pollution. The length of the data span is 11 years from 1983 to 1993. The data of radiation and sunshine rate recorded at 20 meteorological standard stations were used, and in order to investigate a relationship between the depletion rate of solar radiation and air pollution, the concentration data of air pollution observed in Seoul, Pusan, Taegu, Taejon and Kwangju were compiled from 1991 to 1993. Regression coefficient a and b vary from 0.100 to 0.209, from 0.464 to 0.691, and their means are 0.163 and 0.533, respectively. Climatological atmospheric transmissivity is ranged from 0.68 to 0.83, and its mean is 0.75. Atmospheric transmissivity is relatively low in Pusan, Taejon, Kwangju and Inchon which have large population and are highly industrialized. However, that in Chinju, Mokpo, Cheju and Sosan appears to be large compared to the aforementioned stations. Insolation rate of clear days varies from 0.71 to 0.58, and its mean is 0.63. Insolation rate of Kangnung and Chinju are higher than those of Seoul and Pusan by 5%. From the correlation coefficients between depletion rate of solar radiation and air pollution concentration, the most significant factors related to the depletion rate of solar radiation is appeared to be TSP followed by $SO_2$. Ozone shows a negative correlation, End $NO_2$ does not show a obvious correlation with the depletion rate of solar radiation.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.437-446
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• 1995

The temporal and spatial distribution of atmospheric transmissivity and depletion rate of solar radiation are investigated, and are compared to the concentration of several components of air pollution. The length of the data span is 11 years from 1983 to 1993. The data of radiation and sunshine rate recorded at 20 meteorological standard stations were used, and in order to investigate a relationship between the depletion rate of solar radiation and air pollution, the concentration data of air pollution observed in Seoul, Pusan, Taegu, Taejon and Kwangju were compiled from 1991 to 1993. Regression coefficient a and b vary from 0.100 to 0.209, from 0.464 to 0.691, and their means are 0.163 and 0.533, respectively. Climatological atmospheric transmissivity is ranged from 0.68 to 0.83, and its mean is 0.75. Atmospheric transmissivity is relatively low in Pusan, Taejon, Kwangju and Inchon which have large population and are highly industrialized. However, that in Chinju, Mokpo, Cheju and Sosan appears to be large compared to the aforementioned stations. Insolation rate of clear days varies from 0.71 to 0.58, and its mean is 0.63. Insolation rate of Kangnung and Chinju are higher than those of Seoul and Pusan by 5%. From the correlation coefficients between depletion rate of solar radiation and air pollution concentration, the most significant factors related to the depletion rate of solar radiation is appeared to be TSP followed by $SO_2$. Ozone shows a negative correlation, End $NO_2$ does not show a obvious correlation with the depletion rate of solar radiation.