• Journal of Korean Society of Environmental Engineers
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• v.30 no.9
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• pp.948-954
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• 2008

Membrane bioreactor(MBR) processes have been widely applied to wastewater treatment for last decades due to its excellent capability of solid-liquid separation. However, membrane fouling was considered as a limiting factor in wide application of the MBR process. Excess aeration into membrane surface is a common way to control membrane fouling in most MBR. However, the excessively supplied air is easily dissipated in the reactor, which results in consuming energy and thus, it should be modified for effective control of membrane fouling. In this study, cylindrical tube was introduced to MBR in order to use the supplied air effectively. Membrane fibers were immersed into the cylindrical tube. This makes the supplied air non-dissipated in the reactor so that membrane fouling could be controlled economically. Two different air supplying method was employed and compared each other; nozzle and porous diffuser which were located just beneath the membrane module. Transmembrane pressure(TMP) was monitored as a function of airflow rate, flux, and ratio of the tube area and cross-sectioned area of membrane fibers(A$_m$/A$_t$). Flow rate of air and liquid was regulated to obtain slug flow in the cylindrical tube. With the same flow of air supply, nozzle was more effective for controlling membrane fouling than porous diffuser. Accumulation of sludge was observed in the tube with the nozzle, if the air was not suppled sufficiently. Reduction of membrane fouling was dependent upon the ratio, A$_m$/A$_t$. For diffuser, membrane fouling was minimized when A$_m$/A$_t$ was 0.27, but 0.55 for nozzle.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.285-293
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• 2017

The purpose of this study is to examine the relationship between the Minnesota Multiphasic Personality Inventory(MMPI-2) clinical scales and the self-regulation quotient of the brain quotient. The test in this study was performed by 41 adults over 20 years old and was done using the MMPI-2, which is a self-reporting method. EEG was performed using a 2-channel EEG System at Fp1 and Fp2. The analysis showed a negative correlation between scale 2(D), which is the MMPI-2 clinical scale, and the SRQ(Self Regulation Quotient) relaxation status, which is the related alpha rhythm. Scale3(Hy) showed a positive correlation with the SRQ concentration status and low ${\beta}$ rhythm. Scale7 in the MMPI-2 clinical scales showed a negative correlation with the SRQ relaxation status, which is the alpha rhythm. This means that MMPI-2 and SRQ can be used complementarily in the field of counseling. These results could be interpreted in three ways. First, people with depression are sensitive to other people's attention and evaluation. Therefore, they tend to expend a lot of energy when forming interpersonal relationships, and if they do not learn to relax, their fatigue can easily be increased. Second, people who seek other people's interest and have a cheerful spirit are considered to be highly active. Third, highly stressed people with anxiety and tension seem to easily become tired and their irritation and discomfort may be increased in consequence.

• Journal of the Korean Chemical Society
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• v.41 no.3
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• pp.117-122
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• 1997

On the basis of our previous paper[Bull. Korean Chem. Soc. 1995, 16, 1015], the relative stability, ionization potential, and chemical reaction of the neutral and multiply charged $C_{60}$n ions(n=3+ to 6-) have been investigated by the semi-empirical MNDO method. $C_{60}^{1-}$ has the highest stability. The ionization potential values of the $C_{60}$ ions range from 15.31 eV of $C_{60}^{2+}$ to -13.01 eV of $C_{60}^{6-}$. These values show a linear relationship according to charges. The average IP per charge is 3.15 eV from our calculations and 3.22 eV from the linear function of IP. A charge- or electron-transfer reaction of $C_{60}^{n+}$ will only occur if the ionization potential of any guest molecule is lower than the electron affinity of the host $C_{60}^{n+}$. If the energy gap between ionization potential and electron affinity, ${\Delta}_{IP-EA}$, is high, charge-transfer reactions arise by the charge-controlled effect. However, if ${\Delta}_{IP-EA}$ is low, electron-transfer reactions arise by the frontier-controlled effect.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.2
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• pp.125-136
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• 2006

Statement of problem. The success of the bonding between electroforming gold and resin is dependent on the surface-conditioning technique but its effective technique has net been studied widely. Purpose. The purpose of the study was to evaluate the bond strength between the electroforming gold and resin with varying the surface-conditioning technique. Materials and methods. Sixty rectangular shaped metal specimens were made and one side of each specimen were gold hard plated. The sand-blasted specimens were divided into four experimental groups with fifteen specimens in each group and were treated as follows. Group 1: Silicoating (Rocatec, 3M ESPE)+ Sinfony (3M ESPE), Group 2: SR Link+ SR Adoro (Ivoclar Vivadent), Group 3: Tin plating (Microtin, Danville Engineering)+ SR Link+ SR Adoro, Group 4: Tin plating (Micro tin, Danville Engineering)+ Silicoating (Rocatec)+ Sinfony. Shear bond strength at metal-resin interface were measured using universal testing machine. Energy Dispersive x-ray analysis was done and scanning electron microscope images were taken and observed. Results and Conclusion. The following conclusions were drawn. 1. The mean shear bond strength values in order were 11.69MPa (Group 2), 22.35MPa (Group 3), 22.40MPa (Group 1) and 27.71MPa (Group 4). There was no significant difference in Group 1, Group 3 and Group 4(P>0.05). 2. In the EDX line analysis, the Au was detected on the surface of all specimen. $SnO_2$ showed on the surface of Group 2 and $SiO_2$ was detected on the surface of Group 1. 3. Increasing of roughness by sandblasting(Group 2), formation of micro-irregularities and tin crystals by electrolytic tin plating(Group 3) and formation of surface irregularities and $SiO_2$ layer(Group 1,4) were observed in SEM photo. 4. Tin plating(Group 3) and Rocatec treatment(Group 1) showed clinically effective shear bond strength(>20MPa), but when the two surface conditioning method were used together higher bond strength were achieved.

• Journal of Astronomy and Space Sciences
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• v.35 no.3
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• pp.201-210
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• 2018

The characterization of detectors installed in space- and ground-based instruments is important to evaluate the system performance. We report the development of a detector performance test system for astronomical applications using the Andor iKon M CCD camera. The performance test system consists of a light source, monochromator, integrating sphere, and power meters. We adopted the Czerny-Tuner monochromator with three ruled gratings and one mirror, which covers a spectral range of 200-9,000 nm with a spectral resolution of ~1 nm in the visible region. Various detector characteristics, such as the quantum efficiency, sensitivity, and noise, can be measured in wide wavelength ranges from the visible to mid-infrared regions. We evaluated the Korea Astronomy and Space Science Institute (KASI) detector performance test system by using the performance verification of the Andor iKon-M CCD camera. The test procedure includes measurements of the conversion gain ($2.86e^-/ADU$), full well capacity ($130K\;e^-$), nonlinearity, and pixel defects. We also estimated the read noise, dark current, and quantum efficiency as a function of the temperature. The lowest measured read noise is $12e^-$. The dark current at 223 K was determined to be $7e^-/s/pix$ and its doubling temperature is $5.3^{\circ}C{\pm}0.2^{\circ}C$ at an activation energy of 0.6 eV. The maximum quantum efficiency at 223 K was estimated to be $93%{\pm}2%$. We proved that the quantum efficiency is sensitive to the operating temperature. It varies up to 5 % in the visible region, while the variation increases to 30 % in the near-infrared region. Based on the comparison of our results with the test report by the vendor, we conclude that our performance test results are consistent with those from the vendor considering the test environment. We also confirmed that the KASI detector performance test system is reliable and our measurement method and analysis are accurate.

• Journal of Wetlands Research
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• v.13 no.2
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• pp.343-353
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• 2011

Variations of load in both DOM and RDOM of inflowing rivers to lakes were in the range of 5.01-7.29(${\times}10^2$ kg/day) for AD lake and 1.23-3.75(${\times}10^3$ kg/day) for JY lake during the research period excluding the period directly affected by the strong rainy season and the monsoon and typhoon season. We observed a good relationship($R^2$ > 0.8) between SS load and DOM load (including RDOM) in both inflowing rivers to JY lake. Therefore, it was determined that SS would be an alternative parameter with a rapid and energy-efficient method for the analysis of both DOC and RDOC, which require the analytical equipment and a long time period. Both AD lake and JY lake may act as a DOM(including RDOM) source through primary production in the fall season. Because AD lake and JY lake may not act as a DOM buffer zone, both lakes couldn't control the DOM and RDOM in spring before the rainy season. Therefore to improve water quality in downstream rivers is needed to remove pollutants such as DOM and RDOM before inflowing to these lakes in upstream rivers, or to have the unique landscape of wetlands as a buffer zone.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.165-174
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• 2011

This research aims at the optimal constitution of sensors required to identify the structural shortcoming of roller-coaster. In this research we analyzed the dynamic characteristics of roller-coaster by three dimensional FE modelling, decided on the appropriate location and number of sensors through optimal transducer theory, abstracted the mathematical value of modal features before and after damage on the basis of optimally placed and numbered sensors. and then presented it as a primary information about the basic structure which would be applied to damage estimation. As a target structure, the roller-coater at Seoul Children's Grand Park was chosen and built as a model reduced by one twentieth in size. In order to consider the Kinetics features particular to the roller-coaster structure, we made an exact three-dimensional FE modelling for the model structure by means of Spline function. As for the proper location and number of sensors, it was done by applying EIM and EOT. We also estimated the damage from the combination of strength, flexibility, and model corelation after abstracting the value of modal features. Finally the optimal transducer theory presented here in this research was proved to be valid, and the structural damage was well identified through changes in strength and flexibility. As a result, we were able to present the optimal constitution of sensors needed for the analysis of dynamic characteristics and the development of techniques in dynamic characteristics, which would ultimately contribute to the development of health monitoring for roller-coaster.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.547-553
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• 2017

This study focused on the difference of photocatalytic performance by the incorporation of Pd into the $TiO_2$ framework and suggested five different catalysts composed of $TiO_2$ and x mol% $Pd-TiO_2$ (x = 0.25, 0.5, 0.75, and 1.0). A typical sol-gel method was used to synthesize catalysts, and the phenol photodegradation performance of each catalysts was evaluated. The physicochemical and optical properties of catalysts were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy/energy dispersive spectrometer (SEM/EDS), ultraviolet/visible spectroscopy (UV/Vis), photoluminescence spectroscopy (PL), and photocurrent measurements. With the addition of Pd ions, the band gap of catalysts was shortened and the charge separation between photogenerated electrons and holes easily also occurred. As a result, the phenol photo-destruction performance over 0.75 mol% $Pd-TiO_2$ catalyst was 3 times higher than that of pure $TiO_2$. This is believed to be due to Pd ions acted as an electron capturing function during photocatalysis.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.7
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• pp.957-966
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• 2017

Objective: To understand the dynamic structure, function, and influence on nutrient metabolism in hosts, it was crucial to assess the genetic potential of gut microbial community in yaks of different ages. Methods: The denaturing gradient gel electrophoresis (DGGE) profiles and Illumina-based metagenomic sequencing on colon contents of 15 semi-domestic yaks were investigated. Unweighted pairwise grouping method with mathematical averages (UPGMA) clustering and principal component analysis (PCA) were used to analyze the DGGE fingerprint. The Illumina sequences were assembled, predicted to genes and functionally annotated, and then classified by querying protein sequences of the genes against the Kyoto encyclopedia of genes and genomes (KEGG) database. Results: Metagenomic sequencing showed that more than 85% of ribosomal RNA (rRNA) gene sequences belonged to the phylum Firmicutes and Bacteroidetes, indicating that the family Ruminococcaceae (46.5%), Rikenellaceae (11.3%), Lachnospiraceae (10.0%), and Bacteroidaceae (6.3%) were dominant gut microbes. Over 50% of non-rRNA gene sequences represented the metabolic pathways of amino acids (14.4%), proteins (12.3%), sugars (11.9%), nucleotides (6.8%), lipids (1.7%), xenobiotics (1.4%), coenzymes, and vitamins (3.6%). Gene functional classification showed that most of enzyme-coding genes were related to cellulose digestion and amino acids metabolic pathways. Conclusion: Yaks' age had a substantial effect on gut microbial composition. Comparative metagenomics of gut microbiota in 0.5-, 1.5-, and 2.5-year-old yaks revealed that the abundance of the class Clostridia, Bacteroidia, and Lentisphaeria, as well as the phylum Firmicutes, Bacteroidetes, Lentisphaerae, Tenericutes, and Cyanobacteria, varied more greatly during yaks' growth, especially in young animals (0.5 and 1.5 years old). Gut microbes, including Bacteroides, Clostridium, and Lentisphaeria, make a contribution to the energy metabolism and synthesis of amino acid, which are essential to the normal growth of yaks.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.51-56
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• 2008

The waveform inversion for isotropic media has ever been studied since the 1980s, but there has been few studies for anisotropic media. We present a seismic waveform inversion algorithm for 2-D heterogeneous transversely isotropic structures. A cell-based finite difference algorithm for anisotropic media in time domain is adopted. The steepest descent during the non-linear iterative inversion approach is obtained by backpropagating residual errors using a reverse time migration technique. For scaling the gradient of a misfit function, we use the pseudo Hessian matrix which is assumed to neglect the zero-lag auto-correlation terms of impulse responses in the approximate Hessian matrix of the Gauss-Newton method. We demonstrate the use of these waveform inversion algorithm by applying them to a two layer model and the anisotropic Marmousi model data. With numerical examples, we show that it's difficult to converge to the true model when we assumed that anisotropic media are isotropic. Therefore, it is expected that our waveform inversion algorithm for anisotropic media is adequate to interpret real seismic exploration data.