• Advances in Energy Research
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• v.3 no.3
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• pp.157-165
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• 2015

This research investigates the effect of natural dust accumulation on the glass cover of solar thermal energy conversion systems. Four similar, locally manufactured, flat plate solar collectors are used. All collectors are South oriented with tilt angle of $40^{\circ}$. The glass cover of one collector is kept clean of dust during the experimental period while the second collector is cleaned at the beginning of each month. The third collector is cleaned every two months while the fourth collector is kept un-cleaned throughout the experimental period of four months. The calculated parameters are the solar heat gain rates and the corresponding values of the thermal efficiency. The result of the present work indicates that the percentage of fractional reduction of the useful heat gain rate due to dust accumulation during a period of one and two months is 11.4% and 17.0%, respectively. The percentage decrease of thermal efficiency during the same duration periods is 4.0% and 6.1%, respectively. The percentage of fractional reduction of the useful heat gain rate due to dust accumulation during a period of three and four months is 27.8% and 31.9%, respectively. The percentage decrease of monthly thermal efficiency during the same duration period is 10.2% and 11.3%, respectively.

• Macromolecular Research
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• v.17 no.8
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• pp.575-579
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• 2009

Copolymerization of L-lactide and s-caprolactone initiated by tin (II) octoate (Sn(Oct)$_2$) was carried out in supercritical chlorodifluoromethane (R22) with varying reaction conditions (time and temperature) and amounts of monomer and catalyst, under a pressure of 250 bar. The optimum conditions were a reaction time of 10 h and a temperature of 130 $^{\circ}C$, which is similar to the temperature used in bulk copolymerization system. The conversion increased from 56% to 76% by increasing the reaction time from 1 to 10 h. The molecular weight also increased to 75,900 g.mol$^{-1}$ over the same period, while the increased monomer concentration resulted in a high molecular weight of 86,400 g.mol$^{-1}$ and a monomer conversion of 84%. Raising the reaction temperature from 90 to 130 $^{\circ}C$ increased the monomer conversion as well as the poly-L-lactide-co-${\varepsilon}$-caprolactone (PLCL) molecular weight. The variation on the stannous octoate catalyst suggested that less catalyst would decrease the caprolactone content of the polymer.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.1
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• pp.12-21
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• 2021

For successful automatic target recognition(ATR) with synthetic aperture radar(SAR) imagery, SAR target images of the database should have the identical or highly similar resolution with those collected from SAR sensors. However, it is time-consuming or infeasible to construct the multiple databases with different resolutions depending on the operating SAR system. In this paper, an approach for resolution conversion of SAR target images is proposed based on conditional generative adversarial network(cGAN). First, a number of pairs consisting of SAR target images with two different resolutions are obtained via SAR simulation and then used to train the cGAN model. Finally, the model generates the SAR target image whose resolution is converted from the original one. The similarity analysis is performed to validate reliability of the generated images. The cGAN model is further applied to measured MSTAR SAR target images in order to estimate its potential for real application.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.301-309
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• 2022

This work aims to establish some X-ray qualities recommended by the International Standard Organization (ISO) using the half-value layer (HVL) and H_p(10) dosimetry approaches. The HVL values of the following qualities N-60, N-80, N-100, N-150 and N-250 were determined using various attenuation layers. The obtained results were compared to those of reference X-ray beam qualities and a good agreement was found (difference less than 5% for all qualities). The GAMOS (Geant4-based Architecture for Medicine-Oriented Simulations) radiation transport Monte Carlo toolkit was employed to simulate the production of X-ray spectra. The characteristics HVLs, mean energy and the spectral resolution of simulated spectra have been calculated and turned out to be conform to the ISO reference ones (difference less than the limit allowed by ISO). Furthermore, the conversion coefficients from air kerma to personal dose equivalent for simulated and measured spectra were fairly similar (the maximum difference less than 4.2%).

• IMMUNE NETWORK
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• v.16 no.2
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• pp.126-133
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• 2016

Unlike conventional T cells, innate CD8 T cells develop a memory-like phenotype in the thymus and immediately respond upon antigen stimulation, similar to memory T cells. The development of innate CD8 T cells in the thymus is known to require IL-4, which upregulates Eomesodermin (Eomes). These features are similar to that of virtual memory CD8 T cells and IL-4-induced memory-like CD8 T cells generated in the peripheral tissues. However, the relationship between these cell types has not been clearly documented. In the present study, IL-4-induced memory-like CD8 T cells generated in the peripheral tissues were compared with innate CD8 T cells in terms of phenotype and function. When an IL-4/anti-IL-4 antibody complex (IL-4C) was injected into C57BL/6 mice daily for 7 days, the Eomes^hiCXCR3⁺ CD8 T cell population was markedly increased in the peripheral lymphoid organs and blood. These cells were generated from naïve CD8 T cells or accumulated via the expansion of pre-existing CD44^hiCXCR3⁺ CD8 T cells. Initially, the majority of these CXCR3⁺ CD8 T cells expressed low levels of CD44, which was followed by the conversion to the CD44^hi phenotype. This conversion was associated with the acquisition of enhanced effector function. After discontinuation of IL-4C treatment, Eomes expression levels gradually decreased in CXCR3⁺ CD8 T cells. Taken together, the results of this study demonstrate that IL-4-induced memory-like CD8 T cells generated in the peripheral lymphoid tissues are phenotypically and functionally similar to the innate CD8 T cells generated in the thymus.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.4
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• pp.209-216
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• 1996

In this paper, we propose a learning method of multi-layer perceptrons (MLPs) with 8-bit data precision. The suggested method uses the cross-entropy cost function to remove the slope term of error signal in output layer. To decrease the possibility of overflows, we use 16-bit weighted sum results into the 8-bit data with appropriate range. In the forwared propagation, the range for bit-conversion is determined using the saturation property of sigmoid function. In the backwared propagation, the range for bit-conversion is derived using the probability density function of back-propagated signal. In a simulation study to classify hadwritten digits in the CEDAR database, our method shows similar generalization performance to the error back-propagation learning with 16-bit precision.

• Journal of the Korean Ceramic Society
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• v.33 no.3
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• pp.332-338
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• 1996

This study was investigated on the recycle feasibility of the waste AC(Ammonium Carbonate) solution produ-ced in a commercial AUC(Ammonium Uranyl Carbonate) conversion plant. AUC particles were produced with the AC solution which was prepared with AC solid-agent instead of ammonia and carbon-dioxide gases. As the results particles of monoclinic shapes has been obtained regardless of the pH change if the carbonate concentration is sufficient in the mother liquore. Also a lot of twinned or aggregated particles were formed in case of the increase of pH in the reaction system but not affected in the change of temperature. Consequen-tly the characteristics of the particles which converted for AUC were produced withAC solution to UO2, particles specific surface area shape sintered density and others were similar to that of the particles which were produced with gases only when the pellets are fabricated in the nuclear fuel manufacturing process So the waste AC solution which is produced in the commercial AUC conversion plant is possible to recycle.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.3
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• pp.516-521
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• 2004

In this paper, the effects of ethanol blended gasoline on emissions and their catalytic conversion efficiencies characteristics were investigated in gasoline engine with an electronic fuel injection. The results showed that the increase of ethanol concentration in the blended fuels brought the reduction of THC and $CO_2$ emissions from the gasoline engine. THC emissions were drastically reduced up to thirty percent. And brake specific fuel consumption was increased. but brake specific energy consumption was similar level. However. unburned ethanol and acetaldehyde emissions increased. The conversion efficiency of Pt/Rh based three-way catalysts and the effect of ethanol on CO and NOx emissions were investigated by the change of engine speed. load and air/fuel ratio. Furthermore, the ethanol blended fuel results in the reduction effect of THC. CO and NOx emissions at idle speed.

• Rapid Communication in Photoscience
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• v.2 no.2
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• pp.52-55
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• 2013

Proteorhodopsin (PR) is a photoinduced proton pump found abundantly in ocean and fresh water habitat, and has an important role in photoenergy conversion to bioenergy in the living cells. Numerous sequences that encode PR protein variants were discovered by environmental genome sequencing and they indicated the high sequence similarity. A new-type of PR (YS-PR) which had been discovered from the surface of Yellow Sea was found to have only 5 amino acid differences from the previously known green-light absorbing PR (GPR) protein, but showed different photochemical properties. This YS-PR showed a 10 nm red-shifted absorption maximum, when compared with GPR. It also showed slower photocycling rate than GPR. However, the photoconversion rate of YS-PR was fast enough to pump protons. Four different amino acids out of 5 were similar to Blue-light absorbing PR (BPR), suggesting that those residues might be responsible for the observed spectral and photoconverting properties.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1759-1762
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• 2003

This paper proposes the method that design CLUT(color look-up table) simultaneously processing gamut mapping and color space conversion using only LUT without complex computation. After we construct LUT composed of scanner gamut and printer gamut, we extend L$\^$*/a$\^$*/b$\^$*/ points based on input L$\^$*/a$\^$*/b$\^$*/ to include input scanner L$\^$*/a$\^$*/b$\^$*/ Input RGB image of scanner is converted into CIEL$\^$*/a$\^$*/b$\^$*/ using regression (unction. CIELAB values of scanner are convened into CMY values including gamut mapping processing without additional gamut mapping using the proposed CLUT. In the experiments, the proposed method resulted in the similar color difference, but reduced the complexity computation compared with processing gamut mapping and color space conversion respectively