• Bulletin of the Korean Chemical Society
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• v.32 no.spc8
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• pp.2906-2910
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• 2011

A fluorescent nucleoside analogue, $^AC$, featuring two non-complementary nucleobases linked through an ethynyl group, was synthesized. The extended ${\pi}$-conjugation imparts $^AC$ with red-shifted absorbance (relative to adenine and cytosine) and pale-blue fluorescence. It spontaneously forms nanoparticles, which exhibit considerably enhanced fluorescence, without the help of any additional stabilizing agent. The DMSO/water ratio was an important factor influencing the construction of the NPs. X-ray crystallography confirmed the structure of $^AC$; dynamic light scattering and scanning electron microscopy confirmed the existence of the nanoparticles.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.291-294
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• 2007

This paper preserts the characteristics of leakage currents flowing through 18 kV zinc oxide (ZnO) surge arrester under the mixed DC and AC voltages. The I-V curves of ZnO surge arrester were measured as a function of the voltage ratio K The I-V curves under the mixed DC and AC voltages lay between the pure DC and AC characteristics, and the cross-over phenomenon in I-V curves was observed at the low current region As a result, the increase of DC component to mixed voltages causes the increase of resistive component of total leakage current th ZnO surge arrester.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1349-1351
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• 2005

In this paper discusses isolation driver of single phase AC-DC reversible power converter The reversible power converter driven by binary combination at different transformer winding ratio by BCD code level. It has a advantage that constructs a control system simply and obtain load current of good quality with out filter circuit and free from noise or isolation for lower switching frequency. In this research, study on current type converter and inverter circuit that consist for possibility of AC-DC/BC-AC multi-level reversible converter.

• Environmental Engineering Research
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• v.24 no.4
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• pp.600-607
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• 2019

Volatile organic compounds (VOCs) are released from various sources and are unsafe for human health. Porous materials are promising candidates for the adsorption of VOCs owing to their increased ratio of surface area to volume. In this study, activated carbon (AC) impregnated cellulose acetate (CA) electrospun mats were synthesized using electrospinning for the removal of VOCs from the air mixture of ACs, and CA solution was electrospun at different proportions (5%, 10%, and 15%) in a single nozzle system. The different AC amounts in the electrospun mats were distributed within the AC fibers. The adsorption capacities were measured for acetone, benzene, and dichloromethane, using quartz crystal microbalance. The results elicited an increasing adsorption capacity trend as a function of the impregnation of ACs in the electrospun mats, while their capacities increased as a function of the AC concentration. Dichloromethane resulted in a faster adsorption process than acetone and benzene owing to its smaller molecular size. VOCs were desorbed with the N₂ gas purging, while VOCs were adsorbed at higher temperatures owing to the increased vapor pressures. The adsorption analysis using Dubinin-Astakhov equation showed that dichloromethane is more strongly adsorbed on mats.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.16 no.2
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• pp.152-157
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• 2005

Background and Objectives : 10 normal Korean native speakers participated subjects to investigate the acoustic and aerodynamic study of Korean fricatives, affricates, and plosives and to make good use of the results for the patients with articulation problems. Materials and Method Their productions of [asa], [as'a], [aca], $[ac^ha]$, (ac'a), (ata) , $[at^ha]$, and [at'a] were analyzed with Lx Speech Studio Program (Laryngogrtaph Ltd, UK) for acoustic analysis and Phonatory Function Analyze. (Nagashima Ltd. Model PS 77H, Tokyo, Japan) for aerodynamic analysis. Results : The results are as follows : 1) Plosives showed higher Qx1 in vocal folds closure ratio than fricatives and affricates. 2) Tense fricatives, affricates, and plosives showed higher Qx2 in vocal folds closure ratio than asperated and 1ax. 3) Asperated showed higher Qx1 in vocal folds closure ratio than tense and 1ax. 4) Asperated showed higer peak flow rate than tense and 1ax. Conclusion This results may be helpful for treatment in articulation disorders.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.2
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• pp.171-177
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• 2011

Purpose: The purpose of this study was to investigate the relationships between reading ability and binocular functions, based on self tests through surveys. The possibility of the reading ability tests used in this study as a tool on the determination about vision efficiency was also evaluated. Methods: Through reading ability tests about 138 university students, 72 students (52.2%) of them were first selected. Through self tests about dyslexia and light sensitivity, 38 students (52.7%) of the first selected students were secondly selected, whose extents are more than 3. Binocular tests were carried out about three groups (high, middle, low) of these secondly selected students. Tests about NPCs, distance and near phoria, amplitude of accommodation, fusional vergence, AC/A ratio, accommodative facility, and vergence facility were performed as binocular tests. Results: NPCs were closest to eyes at high groups. Fusional vergence, AC/A ratio, accommodative facility, and vergence facility of high group showed higher than other groups. The phoria at middle group showed higher than other groups. Conclusions: We found that reading ability and some of binocular functions were closely related. Therefore, vision training, associated with insufficiencies of binocular functions, is expected to improve reading ability.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.205-206
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• 2002

In this paper we examined the contribution of mechanical and electrochemical factors in corrosive wear for Zr-alloy against $Al_2O_3$ ball in $Na_2SO_4$ solution. Normal load and the area of metallic specimen was varied to change the corrosion behavior. At the commence of sliding, the potential drop took place, which increased with load due to the great exposure of fresh surface. Wear volume was linearly proportional to load. The corrosion factor was about 15%. By increasing the Aa/Ac ratio, corrosion factor to total wear decreases and saturates above Aa/Ac=0.15.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.16-21
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• 2012

The growth in IT industry has brought a corresponding rise in the number of connected digital devices in the distribution network. These digital loads lead to AC to DC conversion losses in order to supply power to them. The more the renewable energies and plug-in electrical vehicles penetrated our lives, the more the electrical losses are caused by AC to DC conversion process. Hence, this paper suggests the methodology for evaluating the amount of power supplied according to the ratio of DC power supply and performs an economic analysis of DC distribution system considering grid parity. In here, the cost of carbon emission reduced by renewable energy is also concerned.

• Journal of environmental and Sanitary engineering
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• v.17 no.3
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• pp.99-109
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• 2002

Charcoal $tube/CS_2$ method are more popularly used than any other in the measurement of the working environment for the exposure evaluation of organic solvent, but it is some weak points that the lower accuracy can be obtained on the polar materials and within the range of the low concentration. Thus solvent desorption method has been developed to make accuracy higher and to overcome some weak points. However, because of high price of adsorption tube for thermal desorption and the short of study on its application to the working environment, it is not popularly used in the domestic industrial hygiene fields. This dissertation aims to develop thermal desorption and adsorption tubes for measuring organic solvents in the working environment, by comparing and analyzing breakthrough condition and adsorption capacity with ACF. Specific surface area of ACF used in this study is wider than the one of AC and micropore of ACF related with adsorption has been developed, and adsorption velocity and adsorption amount are very excellent by linking a pore of surface and an inside well into micropore. 1. Result of analysis on physical characteristics of adsorbent, the specific surface area of ACF was 1.3 times higher than that of AC. Distribution ratio of micropore related to adsorption was 94% on ACF and AC. Result of SEM, micropore of the AC is opened to the surface. In contrast, ACF shows that extremely fast adsorption speed. Because of micropore are exposed on the surface and penetrate through each other. 2. Breakthrough characteristics of adsorbents was not different from slop of breakthrough curve. The effluent concentration reaches 10% of initial concentration($C_{out}/C_{in}=0.1$, break point) of ACF was 30~316min longer than that of AC. Therefore, the adsorption capacities of ACF was 1.1~4.6 times higher than that of AC. ACF can be used as a proper adsorbent for measurement of organic solvent.

• Korean Journal of Community Nutrition
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• v.10 no.5
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• pp.592-602
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• 2005

This study was conducted to compare nutrient intakes regarding stages of change in dietary fiber increasing behavior. Subjects were consisted of healthy 383 college students (2S0 females and 133 males) in Kyunggi-Do. Stages of change classified by an algorithm based on 6 items were designed each subjects into one of the 5 stages: precontemplation (PC), contemplation (CO), preparation (PR), action (AC), maintenance (MA). Nutrient intakes were assessed by 24-hr recall method. Regarding the S stages of changes, PR stage comprised the largest group $(39.4\%)$, followed by AC $(33.7\%)$, MA$(14.6\%)$, PC$(7.6\%)$, CO$(34.7\%)$. Female were more belong to either AC or MA. The higher stage of change in dietary fiber increasing behavior, the higher self-efficacy. In all male and female, there were no differences in energy, protein, monounsaturated fatty acids, polyunsaturated fatty acids and cholesterol intakes across the 5 stages. But, fiber, postassuim (K), vitamin A and vitamin C intakes of AC or MA were higer than those of PC, CO and PR $Energy\%$ from fat of $PR(25.4\~26.5\%)$ was higher than $20\%$, and those of AC and MA was lower than the other groups. Dietary P/S and ${\varepsilon}6/{\varepsilon}$ 3 ratios of AC and MA were similar to the recommended ratio. Female of PR had the most total saturated fat and palmitic acid and those of MA had the least. Male of PR had the least $\alpha-LNA\;({\varepsilon}3)$ and total ${\varepsilon}3$ fatty acids and those of MA had the most. In male and female in AC or MA, fiber and K intakes from breakfast, dinner and snack and vitamin C intakes from all meals were higher than those of the other stages. These results of our study confirm differences in stages of change in fiber intake in terms of nutritional status. To have lower $energy\%$ from fat, higher intakes of K, fiber and vitamins, desirable ratio of dietary fatty acids, it needs consistent nutritional education leading to the AC or MA of fiber increasing behavior.