• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.421-421
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• 2006

The light and energy-efficiency of classical liquid crystal displays is notoriously poor due to the use of absorption-based linear polarisers and colour filters. For instance, the light efficiency of PVAL polarisers is typically between 40 and 45 % and the colour filters have a typical efficiency below 35 % which results in a total light and energy-efficiency of the display below 10 %. In the past, a variety of polarizers were developed with an enhanced efficiency in generating linearly polarized light. Typically, these polarizers are based on the polarisationselective reflection, scattering or refraction of light i.e. one polarisation direction of light is directly transmitted to the LCD/viewer and the other polarization direction of light is depolarised and recycled which results in a typical efficiency for generating linearly polarized light of 70-85 %. Also, special colour filters have been proposed based on chiral-nematic reactive mesogens which increase the efficiency of generating colour. Despite the enormous progress in this field, a need persists for improved methods for generating polarized light and colour based on low cost optical components with a high efficiency. Here, the use of holographic phase gratings is reported for the generation of polarized light and colour. The phase grating are recorded in a photopolymer which is coated onto a backor frontlight for LCDs. Typically the recording is performed in the transmisson mode or in the waveguiding mode and slanted phase gratings are generated with their refractive index modulation at an angle between 20o and 45o with the normal of the substrate. It is shown that phase gratings with a high refractive index modulation and a high efficiency can be generated by a proper selection of the photopolymer and illumination conditions. These phase gratings coupleout linearly polarized light with a high contrast (> 100) and the light is directed directly to the LCD/viewer without the need for redirection foils. Dependent on the type of phase grating, the different colours are coupled-out at a slightly different angle which potentially increases the efficiency of classical colour filters. Moreover, the phase gratings are completely transparent in direct view which opens the possibility to use them in frontlights for LCDs. Holographic polarization gratings posses a periodic pattern in the polarization state of light (and not in the intensity of light). A periodic pattern in the polarization direction of linearly polarized light is obtained upon interference of two circularly polarized laser beams. In the second part of the lecture, it is shown that these periodic polarization patterns can be recorded in a linear photo-polymerizable polymer (LPP) and that such an alignment layer induces a period rotation in the director of (reactive and non-reactive) liquid crystals. By a proper design, optical components can be produced with only first order diffraction and with a very high efficiency (>0.98). It is shown that these diffraction gratings are potentially useful in projection displays with a high brightness and energy efficiency

• Journal of Korea Water Resources Association
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• v.33 no.4
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• pp.471-482
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• 2000

Surface energy balance components were evaluated by Landsat TM data and GIS with meteorological data. Calibration and validation for the applicability of this methodology were made through the estimating of the large-scale evapotranspiration (ET). In addition, sensitivity and error analysis was conducted to see the effects of the surface energy balance components on ET and the accuracy of each components. Bochong-chon located on the upper part of Guem River basin was selected as the case study area. Spatial distribution map of ET were produced for five dates: Jan. 1, Apr. 3, May. 10, and Nov. 27, 1995. The study results showed tat ET was greatly varied with the aspect and theland use type on the surface. In the case of having northeast and southeast in the aspect, ET was linearly increased depending on growing net radiation. While surface temperature has a high value, NDVI(Normalized Difference Vegetation Index) has a low value in the vegetated area. Therefore, ground heat flux was increased but ET was relatively decreased. The results of sensitivity and error analysis showed that net radiation is most sensitive and effective, ranging from 12.5% to 23.6% of sensitivity. Furthermore, the surface temperature, air temperature, and wind speed have the significant effects on ET estimation using remotely sensed data.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.418-424
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• 2014

The improved thermal stability and anti-oxidation properties of Lyocell fiber were studied based on flame retardant treatment by using NaCl/$H_3PO_4$ solution. The optimized conditions of flame retardant treatment were studied on various maxing ratio of NaCl and $H_3PO_4$ and the mechanism was proposed through experimental results of thermal stability anti-oxidation. The IPDT (integral procedural decomposition temperature), LOI (limited oxygen index) and $E_a$ (activation energy) increased 23, 30 and 24% respectively via flame retardant treatment. It is noted that thermal stability and anti-oxidation improved based on char and carbon layer formation by dehydrogenation and dissociation of C-C bond resulting the hindrance of oxygen and heat energy into polymer resin. The optimized conditions for efficient flame retardant property of Lyocell fiber were provided using NaCl/$H_3PO_4$ solution and the mechanism was also studied based on experimental results such as IDT (initial decomposition temperature), IPDT, LOI and $E_a$.

• Journal of Korea Foresty Energy
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• v.1 no.2
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• pp.1-19
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• 1981

In order to investigate biomass yield of one-year-old hyblrid poplars, Pripulusalba x P. glandulosa $F_1$ and Populus nigra var. italica x P. maximowiczii $F_1$clones, as energy and fiber resources, dry matter yield, leaf area, leaf area index, dry matter production ability, specific gravity and fiber length and width were measured. Dry matter yield was 1.89 ton/ha for Poplus alba x P. glandulosa $F_1$ and 3.63 ton/ha for Populus nigra via.italica x P. merximowiczii $F_1$ clones in the planting density of 20,000 trees/ha and in the planting density of 40,000 trees/ha was 3.87 ton/ha for Populus alba x P. glandulosa $F_1$and 5.64 ton/ha for Populus nigra var. italica x P. maximowiczii $F_1$ clones. Leaf area index was 1.24mtim2 in the planting density of 20,000 trees/ha and 2.45 m31m3 in the density of 40,000 trees/ha for Populus alba x P. glandulosa $F_1$ clones and it was 1.96 m21m2 in the planting density of 20,000 trees/ha and 3.36 m21m2 in the density of 40,000 trees/ha for the hybrid $F_1$ Populus nigra var. italica x P. maximowiczii clones. The average specific gravity of the hybrid poplars was 0..36 when bark and pith were included and 0.31 when bark and pith were removed in the plot of 20,000 trees/ha and in the 40,000 trees/ha plot showed 0.35 and 0.31 respectively, for Populus alba x P. glandulosa $F_1$clones. It was 0.36 when bark and pith were included and 0.32 when bark and pith were removed in the 20,000 trees/ha plot and in the 40,000 trees/ha plot was 0.34 and 0.31 respectively for Populus nigra var. italica x P. maximowiczii $F_1$clones. The average fiber length was 0.57 mm in the 20,000 trees/ha plot and 0.58 mm in the 40,000 trees/ha plot for Poplus alba x P. glandulosa $F_1$clones and was 0.60 in both plots of 20,000 trees/ha and 40,000 trees/ha for Populus nigra var. italica x P. maximowiczii $F_1$ clones. There is a big clonal variation among those clones studied, showing high selection potential in both species.

• Korean Journal of Community Nutrition
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• v.5 no.2
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• pp.297-306
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• 2000

In order to examine the relationship between the number of different foods consumed and nutrient intake, one-day food consumption were surveyed by 24-hour recall from a sample of 287 individuals(20-49 years) living in Daejon City. The number of consumed food items did not include seasonings except red pepper power, sugar, oil, and soybean paste when used in large amounts(DVS). The number, including all seasonings except salt and vinegar(DVSS), was also counted. Of the total subjects, 43.6%(DVS) or 39.0%(DVSS) consumed 18-23 daily different foods with an average of 20.2 or 22.9, respectively. As the DVS increased, daily intakes of total foods and most food groups were elevated. Cereals however were not changed and eggs were decreased with increasing DVS. Energy and nutrient intakes and their mean adequacy ratio(MAR) and index of nutritional quality(INQ) also show positive correlations with DVS. MAR equal to or greater than($\geq$) 0.75 was taken as a cut-off point for nutritional adequacy. In that case, the mean INQ was shown to be $\geq$1. MRI(10) for energy and 9 nutrients and MAR(3) for Ca, vitamin A, and riboflavin were estimated. Form a regression analysis, when MAR(10) was 0.75, the DVS and DVSS were assumed to be 19.6 and 22.2, respectively. And when MAR(3) was 0.75, the DVS and DVSS were assumed to be 31.6 and 34.6, respectively. However the subjects whose MAR(3) was 0.75(0.7-0.8) 23.8(DVS) or 26.6(DVSS) different foods in average, and their mean intakes of energy and all nutrients, except vitamin A, were ranged at 85-100% of the RDA. Of the 74 subjects who consumed DVS$\geq$24, 24 to 42 numbers took 〈75% RDA of Fe, Ca, riboflavin, and vitamin A. And five of 7 who consumed DVS$\geq$32 took $\geq$125%RDA of protein, which showed concerns of overnutrition in case of DVS$\geq$32. Form the above results it could be suggested that a daily intake of 24-32(or 28) of DVS or 27-35(or 31) of DVSS was recommendable for an optimal nutritional of all nutrients if the variety of food groups and sufficient intake of vitamin A and calcium were emphasized together.

• Journal of the Korean Society of Food Culture
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• v.20 no.3
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• pp.323-330
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• 2005

The purpose of this study was to evaluate the effects of the weight control programme through nutrition education on anthropometry, body composition, dietary behavior, and adipocyte-drived protein in obese elementary school children. The subjects were 17 obese children of OI over 120% from the fourth to sixth grades of elementary school. The subjects were given nutrition education for weight control along with physical and behavioral advices once a week, and the program was 12 weeks long. On the completion of 12 week weight control program, significant decreases in waist and hip circumferences were resulted, however, no changes in body mass index (BMI) and obesity index (OI) were found. Hemoglobin was significantly decreased and HDL-cholesterol was significantly increased. Energy intake was decreased significantly along with intakes of Ca, Fe, folic acid, vitamin B1, vitamin B6, and vitamin C. Meal distribution of energy was changed; % energy from snack significantly from 11.9% to 3.3%. Resistin, leptin, and adiponectin level were not changed; Resistin had a negative correlation with vitamin C intake. Leptin had positive correlations with weight and BMI. Adiponectin was negatively correlated with weight and BMI. In conclusion, nutrition education program for weight control for 12 weeks is effective in changing the dietary behavior, serum profile, and anthropometry in obese elementary children, however, no effect was seen in adipocytokine levels.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.254-259
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• 2021

Optical and electrical characteristics of the fluorocarbon films deposited in a high-density C4F8 plasma under various source powers and pressures were investigated. The F/C ratio of the fluorocarbon film deposited in a high-density C4F8 plasma increased with increasing source power and decreasing pressure due to two-step deposition mechanism. The change in the F/C ratio of the film directly affected the optical and electrical characteristics of the fluorocarbon films deposited in a high-density C4F8 plasma. The refractive index of the fluorocarbon film increased with decreasing source power and increasing pressure contrary to the dependence of the film's F/C ratio on the source power and pressure. This was because the increase in the F/C ratio suppressed electronic polarization and weakened the network structures of the film. The resistivity of the fluorocarbon film showed the same behavior as its F/C ratio. In other words, the resistivity increased with increasing source power and decreasing pressure, resulting from stronger repellence of electrons at higher F/C ratios. This work offers the feasibility of the use of the fluorocarbon films deposited in a high-density C4F8 plasma as an alternative to low dielectric constant materials because the optical and electrical properties of the fluorocarbon film can be directly controlled by its F/C ratio.

• Earthquakes and Structures
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• v.23 no.5
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• pp.445-462
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• 2022

To investigate and evaluate the seismic damage behaviors of steel reinforced recycled concrete (SRRC) filled circular steel tube composite columns, in this study, the cyclic loading tests of 11 composite columns was carried out by using the load-displacement joint control method. The seismic damage process, hysteretic curves and performance indexes of composite columns were observed and obtained. The effects of replacement rates of recycled coarse aggregate (RCA), diameter thickness ratio, axial compression ratio, profile steel ratio and section form of profile steel on the seismic damage behaviors of composite columns were also analyzed in detail. The results show that the failure model of columns is a typical bending failure under the combined action of horizontal loads and vertical loads, and the columns have good energy dissipation capacity and ductility. In addition, the replacement rates of RCA have a certain adverse effect on the seismic bearing capacity, energy consumption and ductility of columns. The seismic damage characteristics of composite columns are revealed according to the failure modes and hysteretic curves. A modified Park-Ang seismic damage model based on the maximum displacement and cumulative energy consumption was proposed, which can consider the adverse effect of RAC on the seismic damage of columns. On this basis, the performance levels of composite columns are divided into five categories, The interlayer displacement angle and damage index are used as the damage quantitative indicators of composite columns, and the displacement angle limits of composite columns at different performance levels under 80% assurance rate are calculated as 1/105, 1/85, 1/65, 1/28, and 1/25 respectively. On this basis, the damage index limits corresponding to each performance level are calculated as 0.045, 0.1, 0.48, 0.8, and 1.0 respectively. Finally, the corresponding relations among the performance levels, damage degrees, interlayer displacement angles and damage indexes of composite columns are established. The conclusions can provide reference for the seismic design of SRRC filled circular steel tube composite columns, it fills the vacancy in the research on seismic damage of steel reinforced recycled concrete (SRRC) filled circular steel tube composite columns.

• Korean Journal of Radiology
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• v.24 no.12
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• pp.1249-1259
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• 2023

Objective: This study aimed to evaluate the clinical outcomes and cost-effectiveness of dual-energy X-ray absorptiometry (DXA) for osteoporosis screening. Materials and Methods: Eligible patients who had and had not undergone DXA screening were identified from among those aged 50 years or older at Kaohsiung Veterans General Hospital, Taiwan. Age, sex, screening year (index year), and Charlson comorbidity index of the DXA and non-DXA groups were matched using inverse probability of treatment weighting (IPTW) for propensity score analysis. For cost-effectiveness analysis, a societal perspective, 1-year cycle length, 20-year time horizon, and discount rate of 2% per year for both effectiveness and costs were adopted in the incremental cost-effectiveness (ICER) model. Results: The outcome analysis included 10337 patients (female:male, 63.8%:36.2%) who were screened for osteoporosis in southern Taiwan between January 1, 2012, and December 31, 2021. The DXA group had significantly better outcomes than the non-DXA group in terms of fragility fractures (7.6% vs. 12.5%, P < 0.001) and mortality (0.6% vs. 4.3%, P < 0.001). The DXA screening strategy gained an ICER of US$ -2794 per quality-adjusted life year (QALY) relative to the non-DXA at the willingness-to-pay threshold of US$ 33004 (Taiwan's per capita gross domestic product). The ICER after stratifying by ages of 50-59, 60-69, 70-79, and ≥ 80 years were US$ -17815, US$ -26862, US$ -28981, and US$ -34816 per QALY, respectively. Conclusion: Using DXA to screen adults aged 50 years or older for osteoporosis resulted in a reduced incidence of fragility fractures, lower mortality rate, and reduced total costs. Screening for osteoporosis is a cost-saving strategy and its effectiveness increases with age. However, caution is needed when generalizing these cost-effectiveness results to all older populations because the study population consisted mainly of women.

• Journal of Theoretical and Applied Mechanics
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• v.3 no.1
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• pp.16-33
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• 2002

A concept of hierarchical modeling, the newest modeling technology. has been introduced early In 1990. This nu technology has a goat potential to advance the capabilities of current computational mechanics. A first step to Implement this concept is to construct hierarchical models, a family of mathematical models which are sequentially connected by a key parameter of the problem under consideration and have different levels in modeling accuracy, and to investigate characteristics In their numerical simulation aspects. Among representative model problems to explore this concept are elastic structures such as beam-, arch-. plate- and shell-like structures because the mechanical behavior through the thickness can be approximated with sequential accuracy by varying the order of thickness polynomials in the displacement or stress fields. But, in the numerical analysis of hierarchical models, two kinds of errors prevail: the modeling error and the numerical approximation errors. To ensure numerical simulation quality, an accurate estimation of these two errors Is definitely essential. Here, a local a posteriori error estimator for elastic structures with thin domain such as plate- and shell-like structures Is derived using element residuals and flux balancing technique. This method guarantees upper bounds for the global error, and also provides accurate local error Indicators for two types of errors, in the energy norm. Comparing to the classical error estimators using flux averaging technique, this shows considerably reliable and accurate effectivity indices. To illustrate the theoretical results and to verify the validity of the proposed error estimator, representative numerical examples are provided.