• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.111.1-111.1
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• 2011

The solar energy is dramatically increasing as the alternative energy source and the silicon(Si) solar cell are used the most. In this study, the improved process and equipment for the metallurgical refinement of multicrystalline Si were evaluated for the inexpensive solar cell. The planar plane and columnar dendrite aheadof the liquid-solid interface position caused the superior segregation of impurities from the Si. The solidification rate and thermal gradient determined the shape of dendrite in solidified Si matrix solidified by the directional solidification(DS) method. To simulate this equipment, the commercial software, PROCAST, was used to solve the solidification rate and thermal gradient. Si was vertically solidified by the DS system with Stober process and up-graded metallurgical grade or metallurgical grade Si was used as the feedstock. The inductively coupled plasma mass spectrometry (ICP) was used to measure the concentration of impurities in the refined Si ingot. According to the result of ICP and simulation, the high thermal gradient between the two phases wasable to increase the solidification rate under the identical level of refinement. Also, the separating heating zone equipped with the melting and solidification zone was effective to maintain the high thermal gradient during the solidification.

• Tribology and Lubricants
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• v.35 no.6
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• pp.350-355
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• 2019

Surface energy is an important factor in determining the performance of application components in terms of preventing adhesion failure between thin films. In this regard, numerous attempts have been made to acquire the desired surface energy through chemical treatment or by using micro/nanostructures. However, such approaches are expected to provide extreme values of surface energy, which may not be suitable in achieving the enhanced performance of applications. In this study, we propose a method to control surface energy by using bilayer metallic film heterostructures. We measure the water contact angle of incompatible (Ni/Ag) and compatible (Zn/Ag) metal pairs under several experimental factors, including thickness, time, and temperature. Furthermore, we conduct Auger electron spectroscopy measurements to investigate the atomic concentration with respect to depth after the change in the water contact angle. The experimental results reveal that three parameters, namely, compatibility, film thickness, and environmental temperature, are major factors in controlling the water contact angle. Thus, we experimentally demonstrate that controlling these three parameters can provide the approximate desired water contact angle. This result is expected to aid in the performance enhancement of a wide range of application components, where control of surface energy is required.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.38-47
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• 2007

Based upon temperature calibration using the diffusion flame, the temperature and soot concentration of the turbulent flame in a visualized Diesel engine's turbulent flow of flame was qualitatively measured. Two different heads were used to judge the effect of swirl ratio within the combustion chamber. It was possible to measure the highest temperature of the non-swirl head visualized engine which is approximately 2400K, and that the swirl head engine managed up to 2100K. Also, the more the pressure of the spray increases the more the temperature increases due to the improved combustion situation with respect to the visualized diesel engine soot. This experiment also revealed that the KL factor was high where the fuel collided with the walls of the combustion chamber. Moreover the KL factor was high on parts of the chamber where the temperature dropped rapidly.

• Journal of Environmental Impact Assessment
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• v.15 no.6
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• pp.425-433
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• 2006

Instrumental neutron activation analysis was used to measure the concentrations of 27 elements associated with respirable particulate matter (PM10) that were collected from the Third and Fourth Industrial Complex Area of Daejeon City. The distribution patterns of elements were clearly distinguished with their concentrations varying across more than four orders of magnitude. The mean for Al were recorded to be the highest value of 1,527 $ng/m^3$, while that for In showed the lowest value of 0.1 $ng/m^3$. If compared in terms of enrichment factors, it was found that certain elements (e.g., As, Br, Cl, Cr, I, In, Sb, Se, and Zn) are enriched in PM10 samples of the study site. The results of factor analysis indicated six factors with statistical significance, which may exert dominant controls on regulating the elemental concentration levels in the study area.

• Smart Structures and Systems
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• v.8 no.1
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• pp.53-67
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• 2011

Human state in human-machine systems highly affects the overall system performance, and should be detected and monitored. Physiological cues are essential indicators of human state and useful for the purpose of monitoring. The study presented in this paper was focused on developing a bio-inspired sensing system, i.e., Nano-Skin, to non-intrusively measure physiological cues on human-machine contact surfaces to detect human state. The paper is presented in three parts. The first part is to analyze the relationship between human state and physiological cues, and to introduce the conceptual design of Nano-Skin. Generally, heart rate, skin conductance, skin temperature, operating force, blood alcohol concentration, sweat rate, and electromyography are closely related with human state. They can be measured through human-machine contact surfaces using Nano-Skin. The second part is to discuss the technologies for skin temperature measurement. The third part is to introduce the design and manufacture of the Nano-Skin for skin temperature measurement. Experiments were performed to verify the performance of the Nano-Skin in temperature measurement. Overall, the study concludes that Nano-Skin is a promising product for measuring physiological cues on human-machine contact surfaces to detect human state.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.4
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• pp.75-85
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• 2005

A study was performed to examine the effects of reclaimed-water irrigation on microorganism con-centration in ponded-water of paddy rice plots. Several treatments were used and each one was triplicated to evaluate the change of indicator microorganisms (total coliforms (TC), fecal coliforms FC), and E. coli) concentrations in 2003 and 2004 growing seasons. Their concentrations increased significantly right after irrigation, but decreased about $45\%$ in 24 hours. It implies that agricultural activities such as plowing and fertilizing should be practiced one or two days after irrigation considering health-risks. Treatments with UV-disinfected water irrigation demonstrated significantly lower concentrations than others including control plots where natural surface water was irrigated. The monitoring results from actual paddy rice fields and experimental paddy plots showed that concentrations of indicator microorganisms ranged from $10^2\;to\;10^5$ MPN/100mL. A comprehensive assessment of existing agricultural practices and a thorough monitoring in the field as well as treatment-plots are recommended to make more realistic national guidelines more applicable. UV-disinfected water irrigation reduced microorganism concentrations in paddy fields down to below the concentration of conventional paddy rice culture, and is thought to be an effective and feasible measure fur agricultural reuse of secondary effluent.

• Analytical Science and Technology
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• v.7 no.3
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• pp.349-359
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• 1994

A gas chromatographic method for analyzing the gas odorants concentration in natural gas was studied. Eight odorants involving TBM and THT were completely separated by using OV-10 column. The optimization of several interrelated key parameters affecting the response of FPD such as hydrogen flow rate, air flow rate and detector temperature were accomplished. A permeation device was used to obtain calibration curves of TBM and THT. This analytical method has applied to measure TBM and THT used as a natural gas odorant blend in natural gas pipeline. In order to elucidate the relationship between odor level and odorant level feasibility test of fragrance meter was demonstrated.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.5
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• pp.355-360
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• 2012

A simple, sensitive and reproducible high-performance liquid chromatography (HPLC) method has been validated for determining concentrations of glutamate, glycine, and alanine in human plasma. Proteins in plasma were precipitated with perchloric acid, followed by derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). Simultaneous analysis of glutamate, glycine, and alanine is achieved using reversed-phase HPLC conditions and ultraviolet detection. Excellent linearity was observed for these three amino acids over their concentration ranges with correlation coefficients (r)>0.999. The intra- and inter-day precision were below 10%. This method utilizes quality control samples and demonstrates excellent plasma recovery and accuracy. The developed method has been successfully applied to measure plasma glutamate, glycine, and alanine in twenty volunteers.

• Journal of Pharmacopuncture
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• v.19 no.1
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• pp.45-50
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• 2016

Objectives: The purpose of this study was to investigate the antifungal effect of bee venom (BV) and sweet bee venom (SBV) against Candida albicans (C. albicans) clinical isolates. Methods: In this study, BV and SBV were examined for antifungal activities against the Korean Collection for Type Cultures (KCTC) strain and 10 clinical isolates of C. albicans. The disk diffusion method was used to measure the antifungal activity and minimum inhibitory concentration (MIC) assays were performed by using a broth microdilution method. Also, a killing curve assay was conducted to investigate the kinetics of the anti-fungal action. Results: BV and SBV showed antifungal activity against 10 clinical isolates of C. albicans that were cultured from blood and the vagina by using disk diffusion method. The MIC values obtained for clinical isolates by using the broth microdilution method varied from $62.5{\mu}g/mL$ to $125{\mu}g/mL$ for BV and from $15.63{\mu}g/mL$ to $62.5{\mu}g/mL$ for SBV. In the killing-curve assay, SBV behaved as amphotericin B, which was used as positive control, did. The antifungal efficacy of SBV was much higher than that of BV. Conclusion: BV and SBV showed antifungal activity against C. albicans clinical strains that were isolated from blood and the vagina. Especially, SBV might be a candidate for a new antifungal agent against C. albicans clinical isolates.

• Journal of the Korean Applied Science and Technology
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• v.27 no.1
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• pp.70-75
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• 2010

Scale generation in the inside of a pipe IS restricted by reduction and oxidation(REDOX) reaction of alloyed metal of Cu-Zn. To measure the scale generating rate in the 1.67 mm of inside diameter of stainless steel tube, 300 ppm of $CaCO_3$ solution is circulated in the REDOX reactor and stainless steel tube in the order. In the case of $CaCO_3$ solution treated by REDOX reactor, flowing is maintained without plugging in the stainless steel tube, and the concentration of Cu and Zn in the circulating solution showed less than 1 ppm, which is equal to that of untreated by REDOX reactor. The crystal type of $CaCO_3$ generated by crystalline nucleus of Cu or Zn, mostly showed aragonite type.