• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.64.2-64.2
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• 2010

In order to improve the overall power conversion efficiency in dye-sensitized solar cells (DSSCs), it is very important to secure the sufficient surface area of photocatalytic nanoparticles layer for absorbing dye molecules. It is because increasing the amount of dye absorbed generally results in increasing the amount of light harvesting. In this work, we proposed a new method for increasing the specific surface area of photocatalytic titanium oxide ($TiO_2$) nanoparticles by using an inorganic templating method. Salt-$TiO_2$ composite nanoparticles were synthesized in this approach by spray pyrolyzing both the titanium butoxide and sodium chloride solution. After aqueous removal of salt from salt-$TiO_2$ composite nanoparticles, mesoporous $TiO_2$ nanoparticles with pore size of 2~50 nm were formed and then the specific surface area of resulting porous $TiO_2$ nanoparticle was measured by Brunauer-Emmett-Teller (BET) method. Generally, commercially available P-25 with the average primary size of ~25 nm $TiO_2$ nanoparticles was used as an active layer for dye-sensitized solarcells, and the specific surface area of P-25 was found to be ~50 $m^2/g$. On the other hand, the specific surface area of mesoporous $TiO_2$ nanoparticles prepared in this approach was found to be ~286 $m^2/g$, which is 5 times higher than that of P-25. The increased specific surface area of $TiO_2$ nanoparticles will absorb relatively more dye molecules, which can increase the short curcuit current (Jsc) in DSSCs. The influence of nanoporous structures of $TiO_2$ on the performance of DSSCs will be discussed in terms of the amount of dye molecules absorbed, the fill factor, the short circuit current, and the power conversion efficiency.

• Korean Journal of Plant Resources
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• v.32 no.6
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• pp.677-682
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• 2019

Hand leaf thinning for improvement of fruit coloration and quality is one of the most labor-consuming works in Korean apple cultivation. The study was aimed at investigating whether foliar application of two chelate compounds (Cu-EDTA, Fe-EDTA) could defoliate effectively 'Hongro'/M.9 apple leaves and enhance fruit coloration and quality. At 30 days before harvest, foliar spray with two chelate compounds defoliated significantly the apple leaves. Chelate treatments did not affect the leaf chlorophyll content. High concentration of chelates decreased drastically photosynthetic rate of true leaves, and then it stayed in low levels, whereas low levels of chelates reduced sharply the photosynthetic rate but it was gradually restored over time. Cu-EDTA regardless of its concentration triggered higher defoliation compared to Fe-EDTA. Consequently, higher defoliation improved light interception of fruits and accumulated more anthocyanin. Particularly, Cu-EDTA could target mainly fruit cluster leaves which affect directly light interception of the fruits, i.e. more selective defoliants compared to Fe-EDTA. However, 3% Cu-EDTA rather defoliated excessively, accompanying with reduction of fruit weight and soluble solids. Therefore, our results suggest that 1% Cu-EDTA which defoliates properly the fruit cluster leaves could improve coloration and quality of 'Hongro'/M.9 apple fruits.

• Advances in aircraft and spacecraft science
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• v.4 no.1
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• pp.37-52
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• 2017

Gas turbines operating in dusty or sandy environment polluted with micron-sized solid particles are highly prone to blade surface erosion damage in compressor stages and molten sand attack in the hot-sections of turbine stages. Commercial/Military fixed-wing aircraft engines and helicopter engines often have to operate over sandy terrains in the middle eastern countries or in volcanic zones; on the other hand gas turbines in marine applications are subjected to salt spray, while the coal-burning industrial power generation turbines are subjected to fly-ash. The presence of solid particles in the working fluid medium has an adverse effect on the durability of these engines as well as performance. Typical turbine blade damages include blade coating wear, sand glazing, Calcia-Magnesia-Alumina-Silicate (CMAS) attack, oxidation, plugged cooling holes, all of which can cause rapid performance deterioration including loss of aircraft. The focus of this research work is to simulate particle-surface kinetic interaction on typical turbomachinery material targets using non-linear dynamic impact analysis. The objective of this research is to understand the interfacial kinetic behaviors that can provide insights into the physics of particle interactions and to enable leap ahead technologies in material choices and to develop sand-phobic thermal barrier coatings for turbine blades. This paper outlines the research efforts at the U.S Army Research Laboratory to come up with novel turbine blade multifunctional protective coatings that are sand-phobic, sand impact wear resistant, as well as have very low thermal conductivity for improved performance of future gas turbine engines. The research scope includes development of protective coatings for both nickel-based super alloys and ceramic matrix composites.

• Journal of ILASS-Korea
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• v.23 no.3
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• pp.122-127
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• 2018

Recently, registrated passenger cars have increased and were close about seventy million at the end 2017 year in Korea. Among the passenger car using gasoline fuel make up forty six percentage of total registrated vehicles. In this study, investigation on real driving emission characteristics in the passenger car using gasoline fuel with various engine displacements were carried out. The real driving emission characteristics were measured and analyzed by using PEMS (Portable Emission Measurement System). PEMS was composed of gas analyzer, emission flow meter and sample conditioning system et al. Also, test six vehicles were selected to the gasoline passenger car with engine displacement from 1.6L to 3.7L. Two test routes with engine start of cold and hot conditions were applied to analyze the emission characteristics of RDE, respectively. The results show that the $CO_2$ emission have a increasing trend as the engine displacement and vehicle weight. Also, it is guessed that the $CO_2$ emission and vehicle weight were more correlated than the engine displacements. On the other hand, NOx emissions of RDE have not increasing or decreasing tendency according engine displacements or vehicle weight because the activation of three-way catalyst in the gasoline vehicles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.892-897
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• 2020

Previous plastic heat exchangers are expensive because the mold must be newly manufactured depending on the air conditioning space. On the other hand, danpla is so thin that the heat exchange performance is excellent. Moreover, danpla can be used easily in ventilation systems in view of fabrication. This study proposes correlations for the cooling performance of an indirect evaporative cooling system. The experimental apparatus consisted of a heat exchanger, spray nozzle, fan, thermostat, pump, and measuring sensors for temperature, humidity, and airflow rate. The results showed that the effectiveness decreased gradually as the airflow rate increased. In addition, there was an optimal condition in terms of effectiveness. The performance prediction correlations were determined using the experimental data from various conditions. The proposed correlations showed performance accuracies within 4 % error.

• Korean Journal of Human Ecology
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• v.14 no.2
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• pp.293-302
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• 2005

The purpose of this study is to compare hair care behaviors between Korean and Australian women whose individual hair characteristics, social backgrounds, and culture were different from each other. Then, this study also aims to provide some basic data for professionals in the field of beauty education and industry. Data were collected through a survey with 208 Australian females and 392 Korean females. Analyses included t-test, frequency analysis, and one-way ANOVA. The results are as follows: The Korean women mostly had black and brown natural hair, and 68.4% of them had color. On the other hand, the Australian surveyees had brown and dark blonde, and 85.4% of them had color. They both were asked why they were using hair products. The Koreans responded that they were for hair moisturization, while the Australians said they were for producing a hair style they wanted. In addition, the Koreans made the most use of a hair conditioner and hair wax, while the Australian women did a hair spray and gloss. As far as the satisfaction with beauty salon service goes, the Australian respondents showed more service satisfaction than the Koreans on average. The homogeneity of the two nations' average points was t-tested. The result indicated that significant differences existed in the hair shop satisfaction with services, such as dyeing, haircut, blow dry, shampooing and massaging, and staff attitudes.

• The Plant Pathology Journal
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• v.24 no.4
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• pp.453-460
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• 2008

In the course of in vitro and in vivo screening for bioherbicidal agents, a hyphomycete fungus, Myrothecium sp. F0252 was selected as a candidate for the biocontrol of weeds. The isolate was identified as Myrothecium roridum Tode ex. Fries based on the morphological characteristics and 18S ribosomal DNA sequence analysis and registered as Myrothecium roridum F0252. In order to evaluate the in vitro effect of M. roridum F0252 on germination of ladino clover and white clover (Trifolium repens L.) seeds, spore solution of the fungus was employed in two concentrations, $6.5{\times}10^6$ and $2.5{\times}10^7$ spores per mL and then inoculated to the seeds. The fungal spores inhibited the seed germination, infected the seedlings, and caused an abnormal withering and inhibition of seedling growth. In addition, when the herbicidal activity of crude ethyl acetate extract from the liquid culture was assessed on a mini-plant, duck-weed (Lemna paucicostata (L.) Hegelm.), the extract showed high inhibitory effect at the level of $12.5{\mu}g$ per mL. On the other hand, in vivo herbicidal activity of M. roridum F0252 was evaluated by a whole plant spray method. M. roridum F0252 exhibited strong and broad-spectrum herbicidal activity. The herbicidal values ranged from 95-100% against 7 weeds, including Abutilon avicennae and Xanthium strumarium, and 70-80% against Digitaria sanguinalis and Sagittaria pygmaea. When the nutritional utilization (95 carbon sources) pattern of M. roridum F0252 was investigated, it varied with water activity ($a_w$) and temperature conditions, supplying good, basic information in regard to nutritional utilization for proper cultivation and formulation. Our results showed that M. roridum F0252 might be used as a potential biocontrol agent against weedy plants.

• Korean Journal of Environmental Agriculture
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• v.17 no.4
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• pp.306-311
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• 1998

Effects of soluble silicon and surfactants on the development of powdery mildew of cucumber were tested for environmentally safe powdery mildew control. Tested soluble silicon was potassium silicate$(K_2SiO_3)$ and tested commercial surfactants were Jeonchakje, Silhouette, Kaba, and Tween 20. Tested concentrations were 2, 4, 8, 16mM for the soluble silicon, 0.5 and 1.0% for Tween 20, 0.05 and 0.1% for both Jeonchakje and Kaba, and 0.03 and 0.07% for Silhouette. Water dilutions of tested materials were sprayed on cucumber (Cucumis sativus) leaves once a week for 4 weeks. From 3 days after the second spray, the diseased area and the numbers of fungal colony were measured from the treated leaves for 6 times at 3-4 days interval. Powdery mildew was less severe on treated cucumber compared to distilled water-treated cucumber (check). In all treatments, diseased area index was proportional to the number of the fungal colony. At the end of investigation, there was severe powdery mildew on check cucumbers. Average 30% of a leaf was colonized by powdery mildew fungus and the average number of the fungal colony per leaf reached to more than 70. On the other hand, none of the treated cucumber suffered severe powdery mildew. The treatments including 8 and 16mM of soluble silicon, doubled concentration of Kaba, and 0.5 and 1.0% of Tween 20 showed more than 80% of control effect compared to water-treated cucumber. In addition, no phytotoxicity was found. Potassium silicate and Tween 20 showed the possibility to replace chemical pesticides for the control of powdery mildew.

• Journal of ILASS-Korea
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• v.20 no.3
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• pp.149-155
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• 2015

With increasing of GDP, the registration number of passenger cars has exceeded 20 million last year in Korea. Especially, the registration number of the diesel engine vehicles has been increasing. However, the WHO(World Health Organization) IARC (International Agency for Research on Cancer) has reported that diesel engine exhaust gas is an one of HAPs, which has carcinogenic for human, and they have designated it to Group 1. To solve this problem, exhaust gas from diesel engines has to be controlled. Thus, it has been controlling by European regulatory standard in Korea. On the other hand, in order to meet the enhanced emission regulations, all manufacturing company applied $NO_x$ control device to vehicles such as EGR (Exhaust Gas Recirculation), SCR (Selective Catalytic Reduction) and so on. However, these devices (EGR, SCR) were operated by difference reaction mechanism respectively, and the composition of exhaust gas would be differenced from that of them. In this study, it was conducted to evaluate variety characteristics on changing of exhaust gas composition by each $NO_x$ control device, and the heavy duty diesel trucks were chosen as experimental vehicles. From the result, it revealed that vehicles (with EGR) were discharged higher THC as 52.5% than that of others (with SCR). However, it did not followed that trend, in the case of CO; it was discharged as 57.2% lower than that of others (with SCR). In the future, these data would be used to apply to efficient $NO_x$ control device for meeting to EURO 6.

• Korean Journal of Agricultural Science
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• v.38 no.3
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• pp.413-419
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• 2011

Recently, the rate of cultivation of such as hairy vetch was increased as a way of reducing the current soil problem. However, the occurrence of insect pest such as bean bugs, Riptortus pedestris, were increased in the field of green manure crops and their injuries to hairy vetch were observed. While minimizing insecticide use for the environmental friendly agriculture, the control of the bean bug can be utilized environmental friendly agricultural materials (EFAMs) in the green manure crop fields. The control effects of some EFAMs and most of chemical insecticides to the bean bug were significantly high. As a result of direct spray of EFAM that contained sophora extract or neem extract, the control effects of six EFAMs were higher than 70% at 120 hours after treatments. Among them, three EFAMs were showed over 90% of control effects. On the other hand, most of chemical insecticides were showed 100% of control effect against the bean bug at 48 hours after treatment. As mortality effects of EFAMs were sloely observed until 120h after treatment, we must use selected EFAMs at the beginnibgs of occurrence and entrance in the field of green manure for effective control of bean bugs.