• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.432.1-432.1
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• 2016

We demonstrated that the power conversion efficiency (PCE) of bilayer solar cell was significantly enhanced by inserting interfacial layer between the organic bilayer film and the Al electrode. Moreover, the water contact angle shows that the bilayer solar cells suffer from the undesirable surface component which limits the charge transport to the Al electrode. The AFM measurement has revealed that the pre- and post-thermal annealing treatments results in different morphologies of the interfacial layer which is critical for the higher PCE of the bilayer solar cells. Furthermore we have investigated the electrical properties of the bilayer solar cells and obtained insights into the detailed device mechanisms. The transient photovoltage measurements suggests that the significantly enhanced Voc is caused by reducing the recombination at the interface between the organic films and the Al electrode. By inserting the TiO2 layer between the bilayer film and Al electrode, the open circuit voltage (Voc) was increased from 0.37 to 0.66V. Consequently, the power conversion efficiency (PCE) of bilayer solar cells was significantly enhanced from 1.23% to 3.71%. As the results, the TiO2 interfacial layer can be used to form an ohmic contact layer, serveing as a blocking layer to prevent the penetration of the Al, and to reduce the recombination at the interface.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.18 no.4
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• pp.488-496
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• 2011

Purpose: To determine the type and degree of effect that a hot footbath has on sleep quality and fatigue level in older Korean adults. Methods: A non-equivalent control group quasi-experimental design was used. Fifty participants from a long-term care facility in Kwangju, South Korea, were randomly selected and assigned to two groups: experimental group (27 participants) and control group (23 participants). The participants in the experimental group received hot footbaths in a temperature-controlled water tub of $42^{\circ}C$. They soaked their feet up to 20cm above the ankles for 30 minutes before going to bed for 3 nights. Actigraphy was used to measure their sleep patterns. The data were analyzed using the SAS program. Results: After the intervention, the total sleep satisfaction rate of the participants increased, while sleep latency and fatigue decreased significantly in the experimental group compared to the control group. Conclusion: The study results suggest that hot footbaths are beneficial for older Korean adults in enhancing sleep quality as well as reducing fatigue. Therefore, hot footbaths are recommended as a nursing intervention to improve sleep quality and to reduce fatigue in older Korean adults.

• Journal of Korean Academy of Nursing
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• v.42 no.3
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• pp.405-413
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• 2012

Purpose: The aim of this study was to explore the effects of A-solution on halitosis and oral status in preoperative NPO patients. Methods: A nonequivalent control group, non-synchronized pretest-posttest design was used in this study. The participants in this study were 66 patients who were admitted for gynecologic surgery. The experimental treatment was to give oral gargling with A-solution, blended essential oils and diluted with distilled water. To identify the experimental treatment effects, halitosis, salivary pH, and oral status were measured by a portable halitosis detector, visual analogue scale, Bromo Thymol Blue (BTB), Bromo Cresol Purple (BCP) test paper and oral assessment guide. Data were analyzed using $X^2$-test, t-test with PASW 18.0 version. Results: Participants were homogeneous before experimental treatment. Objective halitosis in the experimental group, measured by a portable halitosis detector (t=-8.34, p<.001) was significantly lower than the control group. Subjective halitosis was significantly lower in the experimental group (t=-9.29, p<.001). Salivary pH was significantly different between two groups (t=8.81, p<.001). Oral status was significantly better in the experimental group (t=-13.31, p<.001). Conclusion: These findings indicate that oral gargling using A-solution is effective in reducing patient halitosis, and improving oral status.

• The KSFM Journal of Fluid Machinery
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• v.10 no.2 s.41
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• pp.16-21
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• 2007

Potential advantages of using vapor injection in a two stage rotary compressor for a $CO_2$ heat pump water heater system were addressed in this paper by numerical simulation. Vapor separated from a flash tank in the middle of the expansion process can be used for injection into the second stage suction plenum of the compressor to improve the system performance. Vapor injection increases the intermediate pressure between the two stages, thus increasing the first stage compressor work and reducing that of the second stage. As a whole, however, the compressor input power increases due to injected mass flow rate for the second stage. Computer simulation showed that increment of the cooling capacity by vapor injection exceeded that of the compressor work, thus improving the system performance. COP improvement by vapor injection was calculated to be about 5-14% for normal operating conditions. With vapor injection, a maximum COP was found when the displacement volume of the second stage becomes 90-95% of that of the first stage of the compressor.

• Journal of the Korean Electrochemical Society
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• v.18 no.2
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• pp.81-85
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• 2015

A method for degradation of the perchlorate anion ($ClO{_4}^-$) has been studied using electrochemically generated zero-valent iron (ZVI) deposited on a porous carbon electrode. The first strategy of this study is to produce the ZVI via the electrochemical reduction of iron (II) on a porous carbon electrode coated with a conducting polymer, instead of employing expensive $NaBH_4$. The present method produced well distributed ZVI on conducting polymer (polypyrrole thin film) and increased surface area. ZVI surface can be regenerated easily for successive reduction. The second strategy is to apply a mild reducing condition (-0.3 V) to enhance the efficiency of the degradation of perchlorate with ZVI without the evolution of hydrogen. The electrochemically generated ZVI nanoparticles may offer an alternative means for the complete destruction perchlorate without evolution of hydrogen in water with high efficiency and at low cost.

• KSBB Journal
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• v.30 no.6
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• pp.302-306
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• 2015

In this work, the antioxidant activity and total phenolic compound content of 6 fractions of Smallanthus sonchifolius, Agrimonia pilosa, and Lithospermum erythrorhizon extract were investigated. The highest total phenolic compound contents of each plant extracts were obtained from n-butanol ($13.75{\pm}0.21%$) and methylene chloride ($12.89{\pm}1.10%$) fractions (S. sonchifolius), ethyl acetate ($19.69{\pm}1.02%$) and water ($18.72{\pm}0.76%$) fractions (A. pilosa), and n-butanol ($36.26{\pm}1.26%$) and ethyl acetate ($17.66{\pm}0.94%$) fractions (L. erythrorhizon), respectively. As a result of DPPH radical scavenging activity in 10 mg/mL condition, the highest activity were obtained from n-butanol fraction of S. sonchifolius (81.06%), ethyl acetate fraction of A. pilosa (86.32%), and n-butanol fraction of L. erythrorhizon (82.6%), respectively. Also, the highest reducing power was obtained same fractions as well as DPPH adical scavenging activity. Overall, antioxidant activity has relatively closely connected with contents of total phenolic compounds in S. sonchifolius and L. erythrorhizon extracts.

• Journal of the Korean Society of Costume
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• v.65 no.1
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• pp.76-88
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• 2015

Excessive spending and the ever-changing fashion trends lead to an increase in material production to meet consumers' needs, which also in turn, increase the amount of industrial waste and many harmful pollutants. To address this problem, this study aimed to utilize discarded jeans' parts, reconstructing them into edgy and functional designs for everyday products. Six pairs of discarded jeans were collected and were used to create six types of functional products -three types of baskets, a bag, a slipper, and a key-holder. The benefits of up-cycling outweigh recycling because it not only increases the recycling rate, but also decreases the amount of energy and cost, thereby increasing the efficiency in recreating new innovative products. These proposed up-cycling ideas will serve as a great alternative for consumers to actively participate in reducing carbon emission, water usage, and waste to landfill by utilizing used clothing. This will guide how consumers can extend the life of their used clothing, utilize recyclable items more thoroughly, and keep used clothing out of landfills.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1686-1691
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• 2004

The effect of recirculated exhaust gas on performance and exhaust emissions with FGR rate are investigated by using a natural circulation, pressurized draft and water tube boiler with FGR system operating at several boiler loads and over fire air(OFA) damper openings. The purpose of this study is to apply the FGR system to a power plant boiler for reducing $NO_{x}$ emissions. To activate the combustion, the suction damper of two stage combustion system installed in the upper side of wind box is opened by handling the lever between $0^{\circ}$ and $90^{\circ}$ , and the OFA with 0 to 20% into the flame is supplied, as the combustion air supplied to burner is reduced. It is found that the fuel consumption rate divided by evaporation rate does not show an obvious tendency to increase or decrease with rising the FOR rate, and $NO_{x}$ emissions are decreased, at the same OF A damper opening, as FOR rates are elevated and boiler loads are dropped.

• Journal of Energy Engineering
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• v.27 no.3
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• pp.36-40
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• 2018

Climate change is one of the major issues in both the developed and developing world. Greenhouse gas (GHG) emission is one of the implications for climate change. It is increasing rapidly. Although the emission is much less when compared to the rest of the world, Ethiopia has also faced this global issue. The major source for GHG emission in Ethiopia is agriculture. Therefore, the agriculture sector has to be given more attention in Ethiopia. To overcome the problem, Climate-Resilient Green Economy (CRGE) strategy has been initiated. One way of executing this target is to create a sustainable and environmentally friendly pathway to use agricultural byproducts. Sugarcane is one of the major plants in Ethiopia. Its byproducts are bagasse, molasses, and press mud. Since it is a waste product, it is economical and creates a sustainable and green environment by reducing GHG emissions. Sugarcane byproducts have versatile applications like as fuel, as cement replacing material, as a mitigation for expansive soils, as biosorbent for the treatment of water and wastewater and also as a wood material. However, Ethiopia has not used this byproduct massively as it is readily available. This paper reviews the possible applications of sugarcane byproducts to mitigate climate change.

• Journal of Sensor Science and Technology
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• v.22 no.3
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• pp.207-211
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• 2013

In this research, the pH sensor was developed using CNT nanosheet with Nafion coating for the advanced medical sensor such as a blood gas analyzer. The CNT nanosheet was formed by dielectrophoresis and water-meniscus between cantilever-type electrodes. Then, the process of the heat annealing and the Nafion coating was conducted for reducing contact resistance and giving proton selectivity respectively. We measured the response of the pH sensor as the electrolyte-gated CNT-nanosheet field effect transistor. The sensor showed a linear current ratio in a similar range of the normal blood pH. A calibration method for decreasing of the response variation among sensors has also been introduced. Coefficient of variance of the pH sensor was decreased by applying the calibration method. A linear relation between the calibrated response of the sensors and pH variance was also obtained. Finally, the pH sensor with a high resolution was fabricated and we verify the feasibility of the sensor by applying the calibration method.