• Journal of the Korean earth science society
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• v.32 no.4
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• pp.360-372
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• 2011

In order to clarify the advection and dispersion characteristics of volcanic tephra to be emitted from the Mt. Baekdu, several numerical experiments were carried out using three-dimensional atmospheric dynamic model, Weather and Research Forecast (WRF) and Laglangian particles dispersion model FLEXPART. Four different temporally averaged meteorological values including wind speed and direction were used, and their averaged intervals of meteorological values are 1 month, 10 days, and 3days, respectively. Real time simulation without temporal averaging is also established in this study. As averaging time of meteorological elements is longer, wind along the principle direction is stronger. On the other hands, the tangential direction wind tends to be clearer when the time become shorten. Similar tendency was shown in the distribution of volcanic tephra because the dispersion of particles floating in the atmosphere is strongly associated with wind pattern. Wind transporting the volcanic tephra is divided clearly into upper and lower region and almost ash arriving the Korean Peninsula is released under 2 km high above the ground. Since setting up the temporal averaging of meteorological values is one of the critical factors to determine the density of tephra in the air and their surface deposition, reasonable time for averaging meteorological values should be established before the numerical dispersion assessment of volcanic tephra.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.1
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• pp.148-169
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• 1994

The concept of biologic attachment of load-bearing implants has developed over the past decades as an alternative to the difficulties associated with long term implantation using mechanical fixation and bone cement. The choice of implant material is also as critical an element as site preparation or insertion procedure. The properties of implants that affect host tissue responses are not limited to chemical composition alone, but also include shape, surface characteristics, site of implantation, and mechanical interaction with host tissues. Initial mechanical interlocking prevents micromotion and may be a prerequisite for direct bone apposition. A hard tightening of screws does not necessarily mean a stronger fixation and final tightening of the fixtures is dependent on the experience of the operator. Removal torque is lower than insertion torque. The purpose of this study was to investigate differences in the removal torques at the bone-implant interface of polished and sandblasted Titanium. This experiment will give insight into important factors that must be considered when interpreting in vivo screwing forces on implants during the connection of the transmucosal abutments. We evaluated the significance of different surface textures by comparison of the withdrawal forces necessary for removal of otherwise identical rough and polished implants of Titanium and also evaluated interfacial response on the light microscopic level to implant surface. And the priority of the area of insertion on osseointegration were evaluated. 9 Titanium implants - among them, 3 were for the developmental - of either a smooth or rough surface finish were inserted in the dog mandible in the right side. 3 months later Kanon Torque Gauge was used to unscrew the implants. The results were as follows : 1. No significant difference was seen in the removal torque due to variation in surface treatment, 23 Ncm for the sandblasted and 23.33 Ncm for the polished surface (p>0.05). 2. Implants in the anterior (25 Ncm) mandible showed better resistance to unscrewing in comparison to ones in the posterior (18 Ncm) region (p<0.05). 3. Developmental fixtures (22 Ncm) had similar pullout strength to the control group (p>0.05).

• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.184-192
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• 2011

Cultural heritage is the historic symbol implying the life of people and regionality. Accordingly, the study on cultural heritage along the border between Korea and China is a very critical and urgent task for educational purposes as well as to secure historic and cultural awareness and national identity. The border area between Korea and China is classified into the areas along Aprok River and areas along Tumen River where the cultural heritage of various ethnicities is scattered. Accordingly, this study tried to find the approaches to implement and use the exhibition contents for educational purposes as well as visual applications rather than a literary study on cultural heritage in the border area between Korea and China. The results of this study will be the opportunity to enhance the practical understanding of the modern states as well as to learn the cultural awareness of the territory of a modern state and people's awareness of the importance of world heritages. Furthermore, the results of this study will be used as the resources for historic and cultural tours on the web or applications and help to understand the cultural features of Korea and China in the northeastern region as well as historic awareness in educational programs using exhibition materials in a museum.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.9
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• pp.859-866
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• 2010

Nonlinear dynamics of pulsating instability-diffusional-thermal instability with Lewis numbers sufficiently higher than unity-in counterflow diffusion flames, is numerically investigated by imposing a Damkohler number perturbation. The flame evolution exhibits three types of nonlinear behaviors, namely, decaying pulsating behavior, diverging behavior (which leads to extinction), and stable limit-cycle behavior. The stable limit-cycle behavior is observed in counterflow diffusion flames, but not in diffusion flames with a stagnant mixing layer. The critical value of the perturbed Damkohler number, which indicates the region where the three different flame behaviors can be observed, is obtained. A stable simple limit cycle, in which two supercritical Hopf bifurcations exist, is found in a narrow range of Damkohler numbers. As the flame temperature is increased, the stable simple limit cycle disappears and an unstable limit cycle corresponding to subcritical Hopf bifurcation appears. The period-doubling bifurcation is found to occur in a certain range of Damkohler numbers and temperatures, which leads to extend the lower boundary of supercritical Hopf bifurcation.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.537-542
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• 1999

Removal of sulfur compounds in the petroleum products is essential for the prevention of sulfur oxides. However, conventional methods involving catalytic reactions are found to have some limitations in complete removal of harmful sulfur compounds and to require relatively high cost. Recently, desulfurization process using microorganisms is known to be promising in terms of excellent sulfur removal efficiency and reasonably low treatment cost. For the biodesulfurization process to be effective, the solubilization of sulfur compounds into aqueous solution is a prerequisite. In this study, polyoxyethylene nonionic surfactants were used in order to enhance the solubilization of sulfur spectrophotometer. The solubilization of sulfur compounds was found to increase with temperature and to bo abruptly increased at above 1 wt % surfactant solutions. It was also observed that the longer the hydrophobic chain of the surfactant molecule, the higher solubilizing power of a nonionic surfactant. It was found that the Tergitol series surfactants showed higher solubilizing capacity than Neodol series presumably due to the disruption of the regular packing in the hydrocarbon region of the surfactant aggregates.

• Radiation Oncology Journal
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• v.6 no.1
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• pp.93-99
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• 1988

Some modern accerelators provide a dual energy for photon beam treatment. The main advantages of dual energy in the treatment of rectosigmoid or rectal cancer are as fellows. 1. Dose in the critical organ such as small intestine, bladder and genital organ are reduced. 2. Presacral and perineal area is fully covered. Dose distribution analysis such as calculation of dose in a target volume, isocenter, $D_{nax}$ and dose spectrum in any region of interest are possible. Examples of plan are given and results are discussed.

• Journal of Science of Art and Design
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• v.7
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• pp.105-127
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• 2005

This research is on the characteristics and roles of important cities of Germany based on the history of the modern art museum and its possessions. Especially, it is focusing on the modern art museums in the western Germany including Dusseldorf, Koln, and Frankfrut that have shown economic recovery from the Miracle of Rhine; the capital city of Germany, Berlin, as well as Munich, the second capital city of Germany. Here, it harmonizes with the tradition of the past and simultaneously, it spreads the concept and role of the new museum as a forerunner. After the WWII, this is the most active of supporting investment for art museums and authors from the economic development. Also, it represents Germany with its national promotion of culture and arts. The modern art museums of Germany emphasize the mission that they exist for the people and the nation as well as creation of new art culture. These art museums working for national culture and art development do not simply collect and preserve arts. They induce active involvement from the public and keep in mind of national objectives. Here, art museums become and educational setting for the people and a room for new art culture. This research is on Germany modern art museum and it is composed of important 'public institutions' of Germany that critically influence the growth of world-renown authors. After the unification of Germany, Munchen and the western region became an important places centering around new Berlin modern art museum. They are the best places that show the national objectives and regional characteristics. Also, there are art museum educational curriculum and open space for the people by explaining exhibition plans and contents. Furthermore, there are two characteristics of German modern art museums that are noteworthy. Firstly, there are Berlin's Neue Nationalgalerie, Munchen's Pinakothek de Moderne, and Dusseldorf's 'K20' (Kunstsammlung N-Westfalen K20) that are the roots of modern art. These modern art museums exhibit popular author's collection repeatedly. This has a tendency to standardize audiences' view or to make audiences bored. It is becoming more like a trend for art work to appear and disappear. Despite these problems, German modern art museums play a critical role for a new cultural art creation and for the national identity by attempting to show the works of domestic authors as well as an intensive collection of world-renown authors' works. Secondly, there is a role as a new art museum to work together with people. It strives to continuously educate difficult modem arts, exhibits in an open space stimulating interest, participation, and conversations. From these roles, Hamburger Bahnhof Museum fur Gegenwart or Dusseldorf's 'K21, Frankfurt Museum $f\"{u}r$ Moderne Kunst, $Kf\"{o}ln$ Museum Ludwig are given new attention. Here, they emphasize the importance of communicating with the audiences and provides experiences that are different from the original spaces by showing the architecture tecture style of the art museum. In conclusion, German modern art museums attempt various changes by connecting to art education. With art museum activities, there forms a connection between arts and the lives of people, and from this, creative cultural art focused on the art museum borns. This is not only limited to Germany, the U.S., etc. We, too, should pay attention to new art culture creation from changes of role and function of modern art museums.

• Journal of Environmental Policy
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• v.10 no.1
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• pp.3-25
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• 2011

Recently, a number of local governments as well as private organizations have spearheaded the release of animals into the natural ecosystem in Korea. In 2002, most of these animals released were mammals and birds, but the parameter was gradually expanded to include fish, amphibians, and invertebrates in addition to mammals and birds in 2007, with an increased overall number of animals released. Such increase has not only posed ecological, economic, and public health risks, but also yielded an increase in damages incurred by releasing animals historically or ecologically alien to a given region without thorough risk assessment. The most significant cause of such risks was a critical lack of risk management and regulatory schemes addressing the release of animals into the natural ecosystem. In stark contrast, developed countries long before established the requisite risk management and regulatory schemes either by complying with the IUCN/SSC's Guidelines for Re-Introductions or devising them independently. In this context, the current study has examined the release of animals into the natural ecosystem in Korea and, based on the investigation, asserted a strong need for proper risk management. Moreover, the study has presented systematic risk management and regulatory schemes suitable for the Korean milieu based on a comparative analysis of those employed in developed countries.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.9
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• pp.1345-1352
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• 2016

The hindgut of horses is an anaerobic fermentative chamber for a complex and dynamic microbial population, which plays a critical role in health and energy requirements. Research on the gut microbiota of Mongolian horses has not been reported until now as far as we know. Mongolian horse is a major local breed in China. We performed high-throughput sequencing of the 16S rRNA genes V4 hypervariable regions from gut fecal material to characterize the gut microbiota of Mongolian horses and compare them to the microbiota in Thoroughbred horses. Fourteen Mongolian and 19 Thoroughbred horses were used in the study. A total of 593,678 sequence reads were obtained from 33 samples analyzed, which were found to belong to 16 phyla and 75 genera. The bacterial community compositions were similar for the two breeds. Firmicutes (56% in Mongolian horses and 53% in Thoroughbred horses) and Bacteroidetes (33% and 32% respectively) were the most abundant and predominant phyla followed by Spirochaete, Verrucomicrobia, Proteobacteria, and Fibrobacteres. Of these 16 phyla, five (Synergistetes, Planctomycetes, Proteobacteria, TM7, and Chloroflexi) were significantly different (p<0.05) between the two breeds. At the genus level, Treponema was the most abundant genus (43% in Mongolian horses vs 29% in Thoroughbred horses), followed by Ruminococcus, Roseburia, Pseudobutyrivibrio, and Anaeroplasma, which were detected in higher distribution proportion in Mongolian horses than in Thoroughbred horses. In contrast, Oscillibacter, Fibrobacter, Methanocorpusculum, and Succinivibrio levels were lower in Mongolian horses. Among 75 genera, 30 genera were significantly different (p<0.05) between the two breeds. We found that the environment was one of very important factors that influenced horse gut microbiota. These findings provide novel information about the gut microbiota of Mongolian horses and a foundation for future investigations of gut bacterial factors that may influence the development and progression of gastrointestinal disease in horses.

• Progress in Medical Physics
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• v.16 no.4
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• pp.176-182
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• 2005

Stereotactic radiosurgery (SRS) is a technique to deliver a high dose to a target region and a low dose to a critical organ through only one or a few irradiation. The SRS must be planned exactly. Currently the surgery plan is peformed by trial and error method. There are many questions about the reliability and reproducibility of the plan result. This study Improve each step of the Oh's method based on heuristic target shaping to obtain the better result. The target was reconstructed using cylinders with same height and the neighbored cylinders were combined according to the difference of each center and diameter. Then, spheres were packed within each cylinders by the packing rules. Two virtual targets were used to compare this method with Oh's method. As a result, the numbers of isocenter were successfully reduced - more than $35\%$ and $26\%$ - without serious differences of proscription isodose to tumour volume ratio (PITV) and maximum dose to proscription dose ratio (MDPD). This technique using cylinder piling and sphere packing will be a helpful tool to planner in stereotactic radiosurgery.