• Journal of the Korean Geophysical Society
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• v.3 no.1
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• pp.57-66
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• 2000

The location and geometry of the Ulsan Fault play important roles in interpreting tectonic evolution of the southeastern part of the Korean Peninsula. Dipole-dipole electrical resistivity surveys and seismic refraction surveys were carried out in the Yaksoo area, Ulsan in order to measure the thickness of the alluvium covering the Ulsan Fault and to find associated fracture zones and possibly the location of its major fault plane. The collected data were analyzed and interpreted. Some results reported previously by others were also used in this interpretation. No low resistivity anomalies were found in the cross-sectional resistivity image of the survey line located in the east of the Dong River. In contrast, well-developed continuous low resistivity anomalies were detected in the west of the Dong River. This strongly suggests that the major fault plane of the Ulsan Fault is located under or in the west part of the Dong River. Two refraction boundaries corresponding to the underground water level and the bottom of the alluvium were found by refraction surveys carried out on the limited part of the east survey line. The thickness of the alluvium was found to be about 30 m. Small faults in the basement rock identified by reflection surveys were not detected by both resistivity and refraction seismic surveys. This might be explained by assuming that low resistivity anomaly is more closely related to the clay contents than the water contents. On the other hand, it may be resulted by the limited resolution of the resistivity and refraction surveys. Detailed study is required to clarify the reason. Resistivity survey is frequently considered to be a good exploration method to detect subsurface faults. However, it appears to be less useful than reflection seismic survey in this work. In dipole-dipole resistivity survey, the number of separation should be increased to survey deeper subsurface with the same resolution. However, signal to noise ratio decreases as the number of separation increases. In this survey area, the signal to noise ratio of up to sixteen separations was good enough based on the statistical properties of measurements.

• Korean Security Journal
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• no.14
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• pp.517-534
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• 2007

Since the beginning of human society, there have always been struggles and competitions for survival and prosperity, terrorism is not a recent phenomenon, however in modern times it has progressed to reflect the advances in civilization and power structures. At the time of the 9.11 terrorist attacks in the U.S. A., a new world order was in the process of being established after the breakdown of the Cold War era. The attacks drove both the Western and the Islamic worlds into heightened fear of terrorism and war, which threatened the quality of life of the whole mankind. Through two war campaigns against the Islamic world, it seems the U.S. has been pushing its own militaristic security road map of the Greater Middle East democratic initiative, justifying it as a means to retaliate and eradicate the terrorist threats towards themselves. However, with its five-year lopsided victories that cost the nation almost four thousand military casualties, and the war expenses that could match the Vietnam war, the U.S. does not yet seem to be totally emancipated from the fears of terrorism. Terrorism, in itself, is a means of resisting forced rules a form of alternative competition by the weak against the strong, and a way of expressing a dismissive response against dictatorial ideas or orders which allow for no normal changes. Intrinsically, the nature of terrorism is a reaction opposing power logics. Confronted with the absolute military power of the U.S., the Islamic strategies of terrorism have begun to rapidly evolve into a new stage. The new strategies take advantage of their civilization and circumstances, they train and inspire their front-line fighters on the Internet, and issue their orders through the clandestine network of the Al Qaeda operatives. These spontaneously generated strategies have been gained speed among the second, and third Islamic generations, many of whom are now spread throughout western societies. This represents a failure of the power-driven, one-sided overseas security initiatives by the U.S., and is creating a culture of fear and distrust in western societies. It is feared that the U.S. war campaigns have made the clash of religions far worse than before, and may ever lead to global ethnic separations and large-scale population movements. Eventually, it may result in the terrorist groups, enlarged and secretly supported by the huge sums of oil money, driving all mankind into a series of irreparable catastrophes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.6
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• pp.812-813
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• 1995

Lactococcal cells are nutritionally fastidious and thus, generally cultured either in milk or M17 medium (Terzaghi and Sandine, 1975). In this study, Lactococcus cremoris wild-type (KH) and its less­proteolytic mutant (KHA1) cells were grown on the M17 medium or with modified M17 medium by replicated parallel experiments. The modified M17 medium had the same composition as M17 medium, except that lactose was replaced by glucose. Analyses of culture-broth samples, in which the M17 and the modified M17 media were used, were conducted by high-performance liquid chromatography (HPLC). But, working with these media created noisy problems in analyses of samples. Therefore, a new semi-synthetic medium was developed on the basis of nutritional requirements (Morishita et al., 1981). The composition of the semi-synthetic medium determined on the basis of the nutritional requirements and the composition of milk, is presented in Table 1. The composition of M17 medium is also presented and compared in the table. L. cremoris KH and KHA1 cells were grown again on the new synthetic medium containing glucose or lactose. The broth samples were then drawn and analyzed by HPLC. Clearer separations of fermented products were achieved from the new medium than those with the M17 and the modified M17 media. In comparison with the M17 or the modified M17 media, growth on the new medium was good (Kim et al, 1993). Additional fermentations were also carried out at a controlled pH of 7.0, where enhanced growth of lactococcal cells was obtained. In the fermentations, samples were also analyzed for the concentrations of sugar and lactic acid. The results showed that the new synthetic medium was as good as or better than the M 17 and the modified M 17 media. This is because casein hydrolysate in the synthetic medium provided a ready supply of amino acids and peptides for L. cremoris KH and KHA1 cells. Lactic acid bacteria (LAB) including Lactococcal cells have been known to be an effective means of preserving foods, at the same time as giving particular tastes in fields of dairy products. LAB also have always occupied an important place in the technology of sea products, and marine LAB have known to be present in traditional fermented products (Ohhira et al, 1988). To apply the new synthetic medium to marine LAB, two different LAB were isolated from pickled anchovy and pollacks caviar and were grown on the new media in which various concentrations of NaCl $(3, 5, 7 and 10\%)$ added. They were also grown on the medium solution in natural seawater $(35\%o\;salinity)$ and on the solution of natural seawater itself, too. As seen in Fig. 1, Marine LAB were grown best on the synthetic medium solution in natural seawater and the higher concentrations of NaCl were added to the medium, the longer lag-phase of growth profile appeared. Marine LAB in natural seawater were not grown well. From these results, the synthetic medium seems good to cultivate cells which are essential to get salted fish aged. In this study, it showed that the new synthetic medium provided adequate nutrition for L. cremoris KH and KHA1 cells, which have been used as cheese starters (Stadhouders et al, 1988). Using this new medium, the acid production capability of starter cultures could be also measured quantitatively. Thus, this new medium was inferior to the M17 or the modified M17 medium in culturing the cheese starters and in measuring fermentation characteristics of the starter cells. Moreover, this new medium found to be good for selected and well-identified marine LAB which are used in rapid fermentations of low-salted fish.

• Journal of The Korean Astronomical Society
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• v.12 no.1
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• pp.41-70
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• 1979

From $B\ddot{o}hm$-Vitense's atmospheric model calculations, the relations, [$T_e$, (B-V)] and [B.C, (B-V)] with respect to heavy element abundance were obtained. Using these relations and evolutionary model calculations of Rood, and Sweigart and Gross, analytic expressions for some physical parameters relating to the C-M diagrams of globular clusters were derived, and they were applied to 21 globular clusters with observed transition periods of RR Lyrae variables. More than 20 different parameters were examined for each globular cluster. The derived ranges of some basic parameters are as follows; $Y=0.21{\sim}0.33,\;Z=1.5{\times}10^{-4}{\sim}4.5{\times}10^{-3},\;age,\;t=9.5{\sim}19{\times}10^9$ years, mass for red giants, $m_{RG}=0.74m_{\odot}{\sim}0.91m_{\odot}$, mass for RR Lyrae stars, $m_{RR}=0.59m_{\odot}{\sim}0.75m_{\odot}$, the visual magnitude difference between the turnoff point and the horizontal branch (HB), ${\Delta}V_{to}=3.1{\sim}3.4(<{\Delta}V_{to}>=3.32)$, the color of the blue edge of RR Lyrae gap, $(B-V)_{BE}=0.17{\sim}0.21=(<(B-V)_{BE}>=0.18),\;[\frac{m}{L}]_{RR}=-1.7{\sim}-1.9$, mass difference of $m_{RR}$ relative to $m_{RG},(m_{RG}-m_{RR})/m_{RG}=0.0{\sim}0.39$. It was found that the ranges of derived parameters agree reasonably well with the observed ones and those estimated by others. Some important results obtained herein can be summarized as follows; (i) There are considerable variations in the initial helium abundance and in age of globular clusters. (ii) The radial gradient of heavy element abundance does exist for globular clusters as shown by Janes for field stars and open clusters. (iii) The helium abundance seems to have been increased with age by massive star evolution after a considerable amount (Y>0.2) of helium had been attained by the Big-Bang nucleosynthesis, but there is not seen a radial gradient of helium abundance. (iv) A considerable amount of heavy elements ($Z{\sim}10{-3}$) might have been formed in the inner halo ($r_{GC}$<10 kpc) from the earliest galactic co1lapse, and then the heavy element abundance has been slowly enriched towards the galactic center and disk, establishing the radial gradient of heavy element abundance. (v) The final galactic disk formation might have taken much longer by about a half of the galactic age than the halo formation, supporting a slow, inhomogeneous co1lapse model of Larson. (vi) Of the three principal parameters controlling the morphology of C-M diagrams, it was found that the first parameter is heavy clement abundance, the second age and the third helium abundance. (vii) The globular clusters can be divided into three different groups, AI, BI and CII according to Z, Y an d age as well as Dickens' HB types. BI group clusters of HB types 4 and 5 like M 3 and NGC 7006 are the oldest and have the lowest helium abundance of the three groups. And also they appear in the inner halo. On the other hand, the youngest AI clusters have the highest Z and Y, and appear in the innermost halo region and in the disk. (viii) From the result of the clean separations of the clusters into three groups, a three dimensional classification with three parameters, Z, Y and age is prsented. (ix) The anomalous C-M diagrams can be expalined in terms of the three principal parameters. That is, the anomaly of NGC 362 and NGC 7006 is accounted for by the smaller age of the order of $1{\sim}2{\times}10^9$ years rather than by the helium abundance difference, compared with M 3. (x) The difference in two Oosterhoff types I and II can be explained in terms of the mean mass difference of RR Lyrae variables rather than in terms of the helium abundance difference as suggested by Stobie. The mean mass of the variables in Oosterhoff type I clusters is smaller by $0.074m_{\odot}$ which is exactly consistent with Rood's estimate. Since it was found that the mean mass of RR Lyrae stars increases with decreasing Z, the two Oosterhoff types can be explained substantially by the metal abundance difference; the type II has Z<$3.4{\times}10^{-4}$, and the type I has higher Z than the type II.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.39-42
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• 1999

Perfluoropolymers represent the ultimate resistance to hostile chemical environments and high service temperature, attributed to the presence of fluorine in the polymer backbone, i.e. to the high bond energy of C-F and C-C bonds of fluorocarbons. Copolymers of Tetrafluoroethylene (TEE) and 2, 2, 4Trifluoro-5Trifluorometoxy- 1, 3Dioxole (TTD), commercially known as HYFLON AD, are amorphous perfluoropolymers with glass transition temperature (Tg)higher than room temperature, showing a thermal decomposition temperature exceeding 40$0^{\circ}C$. These polymer systems are highly soluble in fluorinated solvents, with low solution viscosities. This property allows the preparation of self-supported and composite membranes with desired membrane thickness. Symmetric and asymmetric perfluoropolymer membranes, made with HYFLON AD, have been prepared and evaluated. Porous and not porous symmetric membranes have been obtained by solvent evaporation with various processing conditions. Asymmetric membranes have been prepared by th wet phase inversion method. Measure of contact angle to distilled water have been carried out. Figure 1 compares experimental results with those of other commercial membranes. Contact angles of about 120$^{\circ}$for our amorphous perfluoropolymer membranes demonstrate that they posses a high hydrophobic character. Measure of contact angles to hexandecane have been also carried out to evaluate the organophobic character. Rsults are reported in Figure 2. The observed strong organophobicity leads to excellent fouling resistance and inertness. Porous membranes with pore size between 30 and 80 nanometers have shown no permeation to water at pressures as high as 10 bars. However high permeation to gases, such as O2, N2 and CO2, and no selectivities were observed. Considering the porous structure of the membrane, this behavior was expected. In consideration of the above properties, possible useful uses in th field of gas- liquid separations are envisaged for these membranes. A particularly promising application is in the field of membrane contactors, equipments in which membranes are used to improve mass transfer coefficients in respect to traditional extraction and absorption processes. Gas permeation properties have been evaluated for asymmetric membranes and composite symmetric ones. Experimental permselectivity values, obtained at different pressure differences, to various single gases are reported in Tab. 1, 2 and 3. Experimental data have been compared with literature data obtained with membranes made with different amorphous perfluoropolymer systems, such as copolymers of Perfluoro2, 2dimethyl dioxole (PDD) and Tetrafluorethylene, commercialized by the Du Pont Company with the trade name of Teflon AF. An interesting linear relationship between permeability and the glass transition temperature of the polymer constituting the membrane has been observed. Results are descussed in terms of polymer chain structure, which affects the presence of voids at molecular scale and their size distribution. Molecular Dyanmics studies are in progress in order to support the understanding of these results. A modified Theodoru- Suter method provided by the Amorphous Cell module of InsightII/Discover was used to determine the chain packing. A completely amorphous polymer box of about 3.5 nm was considered. Last but not least the use of amorphous perfluoropolymer membranes appears to be ideal when separation processes have to be performed in hostile environments, i.e. high temperatures and aggressive non-aqueous media, such as chemicals and solvents. In these cases Hyflon AD membranes can exploit the outstanding resistance of perfluoropolymers.

• Journal of Food Hygiene and Safety
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• v.34 no.5
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• pp.413-420
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• 2019

In this study, a sample preparation method and a simultaneous determination method by ultra-high performance liquid chromatography coupled with tandem mass spectrometry for 9 isomers of chlorogenic acid and arbutin in fruits were developed. The samples were extracted using 90% methanol (pH 3.0), with the solutions being shaken and then sonicated for 10 min each. After centrifugation at 4,000 rpm for 10 min, the extraction was concentrated under a vacuum at $40^{\circ}C$ using a vacuum evaporator. The residue was dissolved in 5 mL of 5% methanol and filtered through a $0.45{\mu}m$ membrane before UHPLC-MS/MS analysis. The separations were performed on a C18 column with gradient elution of water (containing 0.1% formic acid) and methanol (containing 0.1% formic acid). The specificity, linearity, limit of detection, limit of quantification, accuracy, and precision of the proposed methods were also evaluated.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.2
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• pp.63-70
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• 2021

As the government strengthens its policy of separating and discharging packaging materials, consumers are increasingly dissatisfied. In order to increase consumer participation in separate discharge policy of packaging materials, it is necessary to increase the willingness to participate by reducing potential consumer problems such as removal of packaging labels. This study conducted a survey of 300 consumers aged 14 and over who recycle and discharge directly from their homes. Ninety-nine percent of consumers said PET bottles are released separately. However, only 65% of consumers removed labels (attachment labels, shrink labels) and other materials (caps, vinyl coatings, tapes, handles, bases, etc.) during separate discharge process. Nearly 52% of consumers cited 'difficulty of separation' as the main reason for not removing labels and other materials. One-way ANOVA analysis showed that 'strong adhesion', 'removal initiation problem' and 'material strength' had high mean regardless of age, which are major factors impedes label removal. Using shrink labels with perforated lines rather than adhesive labels would be more beneficial to encouraging participation in separate discharge. However, if the shrink labels do not have perforated lines or are difficult to remove, adhesive labels are often easier to remove than shrink labels because of the strong cohesiveness of shrink labels. As a result, how easy it is for consumers to remove the label is more important than technological differences. In order to increase consumer participation in packaging material and label separations, improvements in structural design are needed along with the selection of materials that are easy to separate. This study is meaningful in examining consumer perceptions, deriving problems and suggesting directions for policy improvement.

• Journal of Korean Elementary Science Education
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• v.43 no.1
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• pp.122-135
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• 2024

The purpose of this study was to analyze the examples presented in the "Separation of Mixtures" section of the 2015 revised science authorized textbook introduced in elementary schools in 2022 and to see how the teachers and students understand the concept. To do that, 96 keywords were extracted through three cleansing processes to separate the elements of the mixture presented in the textbook. In order to analyze the teachers' perceptions, 32 teachers at elementary schools in Gyeonggi-do received responses to a survey, and a survey of 92 fourth graders who learned the separation of the mixture with an authorized textbook in 2022 was used for the analysis. As a result, as for the solids, 54 out of 96 separations (56.3%) showed the highest ratio, and the largest number of cases were presented according to the characteristics of the development stage of students. It was followed by living things, liquids, other objects and substances, and gasses. By analyzing the mixture, the structure and the interrelationships between the 96 extracted keywords were systematized through the network analysis, and the connection between the keywords, which were a part of the mixture was analyzed. The teachers partially responded to the separation of the complex mixture presented in the textbook, but most of the students did not recognize it. Because the analysis of the teachers' and students' perceptions of the seven separate categories presented in the survey was not based on a clear conceptual perception of the separation of the mixture, but rather they tended to respond differently for each characteristic of each individual category, it was decided that it was necessary to present clearer examples of the separation of the mixture, so that the students could better understand the concept of separation of mixtures that could be somewhat abstract.