• Microbiology and Biotechnology Letters
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• v.48 no.1
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• pp.48-56
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• 2020

This study aimed to optimize the culture conditions to improve the crude biosurfactant activity of Bacillus pumilus IJ-1, using a 3³ full-factorial design of response surface methodology (RSM). It was found that submerged fermentation of B. pumilus improved the activity of the crude biosurfactant. The factors selected for optimization were NaCl concentration, temperature, and tryptone concentration. Response surface analysis revealed that the fitted quadratic model was statistically significant and produced an adequate R² value (0.9898) and a low probability value (<0.0001). The optimum level for each factor was found to be 0.567% (w/v) NaCl, 21.851℃ and 0.765% (w/v) tryptone, respectively. Crude biosurfactant activity was found to be most affected by tryptone concentration; then temperature, and finally NaCl concentration. Our results may potentially facilitate large-scale biosurfactant production from B. pumilus IJ-1.

• International Commerce and Information Review
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• v.11 no.1
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• pp.177-197
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• 2009

In this study we presented the plans to activate the Internet Shopping Mall for GWmart under its present situation recording a rapid growth in sales and recognized as a local new distribution channel since its early stage, using the analysis that affects the purchases of consumers. On studying the reliance of a shopping mall, only the shopping mall image and the efficiency in providing information are significant. Regarding the concentration on the shopping site by shoppers, what becomes significant are the efficiency in providing information and the convenience in searching for products, which is one of the important factors in increasing sales, does not affect the reliance of a shopping mall and the concentration on the shopping site by shoppers. Therefore, this finding suggests that it is not easy to access the internet shopping mall when consumers go shopping for certain products. Because of this, it is necessary to change the design and structure of internet shopping mall to focus on the consumers. Moreover, this study showed that the efficiency in providing information to customers and the image of the shopping mall do not affect the consumers' intention to purchase, which means that shopping mall lacks in its information service and the management of its structure. To address this, it is required to advance the User Interface and contents of internet shopping mall.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.266-268
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• 2013

In this paper, we study the channel doping concentration characteristics of junctionless nanowire transistors (JLT) using Edison nanowire FET device simulation. JLT has no junctions by very simple fabrication process. And this device has less variability and better electrical properties than classical inversion-mode transistors with PN junctions at the source and drain. In this simulation we use tri-gate structure. Source and drain doping concentration is $10^{20}atoms/cm^3$. The simulation results show that I-V characteristics of JLT change due to the variation of channel doping concentration.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.165-170
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• 2001

The main purpose of this study is to generate a fine copper oxide powder of high purity, with a compact structure and a uniform particle size by a spray pyrolysis process. The raw material is a waste copper chloride solution formed in the manufacturing process of Print Circuit Board (PCB). This study also examines the influences of various factors on the properties of the generated powder. These factors include the reaction temperature, the inflow speed of the raw material solution, the inflow speed of the air, the size of the nozzle tip, and the concentration of the raw material solution. It is discovered that, as the reaction temperature increases from 80$0^{\circ}C$ to 100$0^{\circ}C$ , the particle size of the generated powder increases accordingly, and that the structure of the powder becomes much more compact. When the reaction temperature is 100$0^{\circ}C$, the particle size of the generated powder increases as the concentration of copper in the raw material solution increases to 40g/l, decreases as the concentration increases up to 120g/l, and increases again as the concentration reaches 200g/1. In the case of a lower concentration of the raw material solution, the generated powder appears largely in the form of CuO. As the concentration increases, however, the powder appears largely in the form of CuCl. When the concentration of copper in the raw material solution is 120g/1, the particle size of the generated powder increases as the inflow speed of the raw material solution increases. When the concentration of copper in the raw material solution is 120g/1, there is no evident change in the particle size of the generated powder as the size of the nozzle tip and the air pressure increases. When the concentration is 40g/1, however, the particle size keeps increasing until the air pressure increases to 0.5kg/$\textrm{cm}^2$, but decreases remarkably as the air pressure exceeds 0.5kg/$\textrm{cm}^2$.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1573-1576
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• 2007

ABCV-Py, a new red fluorescent material, in which two identical electron donor (dimethylamino group) and acceptor (cyano group) moieties are linked to two independent biphenyl groups which share the same core phenyl, has been synthesized for use in OLED application. Performance of red doped electroluminescent devices using ABCV-Py as dopant were measured with various host materials, $Alq_3$, CBP, DPVBi, and p-terphenyl. The performance of device with DPVBi host material was better than those with other host materials and high doping concentration could be applied on device with ABCV-Py as dopant.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.1 no.2
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• pp.128-135
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• 1991

To obtain the basic information of environmental working status in mercury industries in Korea, 26 mercury industries were investigated with mercury concentration in air and various factors affecting on workplace environment. The results were as follows : 1. The mean air concentration of mercury was $0.046{\pm}0.035mg/m^3$ in 26 mercury industries. 2. The highest mean air concentration of mercury among 26 mercury industries classified by type of product was found in sodium hydroxide manufacturing industries ($0.054{\pm}0.020mg/m^3$) and the lowest mean was found in mercury battery manufacturing industries ($0.003{\pm}0.002mg/m^3$). 3. While the highest' mean air concentration of mercury was found in manual method ($0.061{\pm}0.041mg/m^3$) among the types of operation method, lowest one was found in automatic method ($0.035{\pm}0.025mg/m^3$). 4. While the mean air concentration of mercury was $0.023{\pm}0.018mg/m^3$ in good clean status of workshop, the mean air concentration of mercury in bad clean status was $0.06{\pm}0.033mg/m^3$. Among various factors affecting on th e air concentration of mercury, clean Iiness of workshop showed statistically significant difference with air concentration of mercury, and automation of workshop and local exhaust ventitlation also played important role in control the air concentration of mercury in the working environment.

• Korean Journal of Remote Sensing
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• v.36 no.4
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• pp.573-586
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• 2020

PM (particulate matter) is of interest to everyone because it can have adverse effects on human health by the infiltration from respiratory to internal organs. To date, many studies have made efforts for the prediction of PM10 and PM2.5 concentrations. Unlike previous studies, we conducted the prediction of tomorrow's PM10 concentration for the Air Korea stations using Chinese PM10 data in addition to the satellite AOD and weather variables. We constructed 230,639 matchups from the raw data over 3 million and built an RF (random forest) model from the matchups to cope with the complexity and nonlinearity. The validation statistics from the blind test showed excellent accuracy with the RMSE (root mean square error) of 9.905 ㎍/㎥ and the CC (correlation coefficient) of 0.918. Moreover, our prediction model showed a stable performance without the dependency on seasons or the degree of PM10 concentration. However, part of coastal areas had a relatively low accuracy, which implies that a dedicated model for coastal areas will be necessary. Additional input variables such as wind direction, precipitation, and air stability should also be incorporated into the prediction model as future work.

• Journal of Environmental Health Sciences
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• v.45 no.1
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• pp.18-29
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• 2019

Objectives: The purpose of this study was to examine the relationship between urinary bisphenol A concentration and allergic diseases in children. Methods: This study was conducted in Seoul, South Korea. We collected urine samples from 231 children from a single elementary school in June 2014. Among these, 69 children with urinary creatinine levels outside the normal range were excluded. Information on allergic diseases was obtained from the parents of the children. Urinary bisphenol A was analyzed using a liquid chromatography tandem mass spectrometer. Logistic regression analysis was used to determine if allergic disease was affected by urinary bisphenol A concentration. Results: Girls had a significantly higher concentration of urinary bisphenol A than did boys (p<0.05). Children of 10-12 years old had a significantly higher concentration of urinary bisphenol A than did children 7-9 years old (p<0.01). Concentration of urinary bisphenol A was increased from underweight to overweight (p<0.05). As the concentration of urinary bisphenol A was increased by $1{\mu}g/L$ or $1{\mu}g/g$ creatinine, the risks of lifetime symptoms of atopic dermatitis in children was 1.22 times (95% CI; 1.05-1.41) or 1.08 times (95% CI; 1.01-1.15). Conclusion: Concentration of urinary bisphenol A was associated with gender, age, body mass index, and allergic disease. Particularly, urinary bisphenol A concentration was associated with lifetime symptoms of atopic dermatitis. The findings of this study could contribute to the management of health effects among sensitive groups such as children.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.177-184
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• 2001

Combustion using oxygen enriched air is an energy saving technology that can increase thermal efficiency by the improvement of burning rate and high temperature flame. But information about it is not so enough yet. Flame figure, temperature distribution and emission concentration were measured with oxygen enriched concentration and swirl number in a turbulent diffusion flame to investigate the combustion characteristics. The results showed that flame figure became different as long as oxygen enriched concentration varied and that concentration of NO increased suddenly around $O_2$ 60%.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.1
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• pp.61-69
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• 2014

In this study spatial analysis of PM10 was performed to Particulate Materials(PM) less than $10{\mu}m$ in diameter in Seoul city. Because PM10 are responsible for the increasing mortality rate of lung cancer and cardiovascular diseases, spatial distribution of PM10 are special interest in air pollution of Seoul. In this study, spatial analysis of Particulate Materials were monitored by monthly averaged PM10 concentration of 2010, 2011. The monthly spatial patterns of PM10 showed the west area of Seoul(Youngdungpo) higher PM10 concentration than northern part of Seoul in early spring and winter seasons. In the comparison of PM10 concentration distribution patterns in 2010 and 2011, the PM10 concentration of 2011 at Gangnam and Songpa-gu were more increased than yearly averaged patterns of 2010. The distribution patterns of PM10 in Seoul city showed the high concentration PM10 of several areas with Youngdungpo-gu, Gangnam-gu and Cheongnyangni. Therefore we need to establish PM10 management strategy for these area.