• Geomechanics and Engineering
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• v.14 no.1
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• pp.19-27
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• 2018

It follows from the basic principles of mechanics of deformable solids relating to the strength, stability and propagation of elastic waves that the Earth's inner core cannot exist in the form of a spherical structure in the assumed thermobaric conditions and calculation values of physico-mechanical parameters. Pressure level reaches a value that is significantly greater than the theoretical limit of medium strength in the model approximations at the surface of the sphere of the inner core. On the other hand, equilibrium state of the sphere is unstable on the geometric forming at much lower loads under the influence of the "dead" surface loads. In case of the action of "follower" loads, the assumed pressure value on the surface of the sphere is comparable with the value of the critical load of "internal" instability. In these cases, due to the instability of the equilibrium state, propagation of homogeneous deformations becomes uneven in the sphere. Moreover, the elastic waves with actual velocity cannot propagate in such conditions in solid medium. Violation of these fundamental conditions of mechanics required in determining the physical and mechanical properties of the medium should be taken into account in the integrated interpretations of seismic and laboratory (experimental) data. In this case, application of the linear theory of elasticity and elastic waves does not ensure the reliability of results on the structure and composition of the Earth's core despite compliance with the required integral conditions on the mass, moment of inertia and natural oscillations of the Earth.

• Journal of the Korean Society of Visualization
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• v.7 no.2
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• pp.22-27
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• 2010

The delayed gastric emptying flows have been visualized in this study when a gastric graft replaced an esophagus after esophagectomy. To construct visualization models for gastric grafts, the path data of gastric graft were extracted from the CT images for real patients and then the experimental models were made from silicone tube by considering elasticity of real stomach. During experiments, 200 ml of water or glycerin was poured into the gastric graft model and the gastric emptying time for total volume of fluid to pass pylorus was measured from the successive images captured by a high speed CCD. The gastric emptying time was compared according to the change of diameter and path (front or rear path) of gastric graft, and pyloroplasty or not. In case that the pyloroplasty was not conducted, the smaller was the diameter of gastric graft, the shorter was the gastric emptying time. However, if the pyloroplasty was conducted, the larger diameter of gastric graft was better for the gastric emptying. Although the rear path gave rise to longer gastric emptying time than the front path, it did not matter, if the pyloroplasty was conducted.

• The Korean Journal of Food And Nutrition
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• v.28 no.6
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• pp.1011-1018
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• 2015

The effects of mixing speed (3, 6 and 10 speed) and time (2, 5 and 10 min) on the dynamic viscoelasticity of dough and the baking properties of gluten-free rice bread were investigated. The specific gravity of the dough was not affected by the mixing speed and time before and after fermentation. The elasticity (G') and viscosity (G") of the dough increased and the tan ${\delta}$ (G"/G') decreased with higher mixing speeds and longer mixing times. The specific volume of the gluten-free rice bread was affected by the mixing time in response surface methodology (RSM). The hardness of the gluten-free rice bread showed a decreasing trend as the specific volume for the gluten-free rice bread increased. The appearance of the gluten-free rice bread was symmetrical at high mixing speeds and long mixing times. Overall results indicated that the quality of gluten-free rice bread could be improved by controlling the mixing speeds and mixing times for the dough.

• Fire Science and Engineering
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• v.24 no.3
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• pp.106-112
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• 2010

This study carried out the motion analysis of auto closing systems as basis study for development of auto closing systems for door in smoke control zone. This study established process of auto closing systems and analysis theory based on kinematics mechanism thesis and mechanism modelling of auto closing control units. And this study established engineering data construction and a source technology that can design each element of auto closing control units that choose closing force units through motion analysis simulation based on analysis theory. Therefore, it can give flexibility and elasticity of auto closing units development from this study. Also, it sees that can ready control means and technological countermeasure of smoke by development of auto closing units and secure high reliancity and stability of smoke control systems.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.181-182
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• 2016

We developed eco-friendly lightweight concrete in order to apply eco-friendly lightweight concrete into structural wall or slab of shallow depth urban railway system. However, since lightweight aggregate has different structural feature of porous and it has been overvalued at current KS standard when applied, we did compare the characteristics of freezing and thawing of normal weight aggregate concrete by comparative test method(KS, ASTM). According to test method, there was a big difference of dynamic elastic modulus in lightweight concrete rather than in normal weight aggregate concrete. The big absorption factor in lightweight aggregate is main reason for that. For more detail, in KS law in which only 14 days water curing is carried out, the big amount of moisture in lightweight aggregate is frozen and high heaving pressure occurs and finally that lead to destruction of lightweight concrete. Therefore, it is considered that in case of lightweight concrete, resistibility against freezing and thawing has been undervalued in domestic KS law compared to ASTM law, which is overseas standard. So, a variety of examination about testing criteria and rule would be necessary for exact assessment of lightweight concrete.

• Ocean Systems Engineering
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• v.1 no.1
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• pp.95-111
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• 2011

Increasing numbers of floating offshore wind turbines are planned and designed these days due to their high potential in massive generation of clean energy from water depth deeper than 50 m. In the present study, a numerical prediction tool has been developed for the fully-coupled dynamic analysis of FOWTs in time domain including aero-blade-tower dynamics and control, mooring dynamics, and platform motions. In particular, the focus of the present study is paid to the dynamic coupling between the rotor and floater and the coupled case is compared against the uncoupled case so that their dynamic coupling effects can be identified. For this purpose, a mono-column mini TLP with 1.5MW turbine for 80m water depth is selected as an example. The time histories and spectra of the FOWT motions and accelerations as well as tether top-tensions are presented for the given collinear wind-wave condition. When compared with the uncoupled analysis, both standard deviations and maximum values of the floater-responses/tower-accelerations and tether tensions are appreciably increased as a result of the rotor-floater dynamic coupling, which may influence the overall design including fatigue-life estimation especially when larger blades are to be used.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.24-30
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• 1998

Inhibitory effects of the new material obtained from Areca catechu seed (CC-516) according to a special process, and its applicability to the skin as a cosmetic raw material in terms of its efficacy were presented. Areca catechu extract out of 150 medicinal plants, exhibited high inhibitory effect on the porcine pancreatic elastase ($IC_{50}$ : $40.8{\mu}$g/ml). It also had an inhibitory effect on the human leukocyte elastase ($IC_{50}$ : 48.1$\mu$g/ml), hyaluronidase ($IC_{50}$ : $416{\mu}$g/ml), antioxidative activity ($IC_{50}$ : $45.4\mu$g/ml) and free radical scavenging activity ($SC_{50}$ : $10.2{\mu}$g/ml). The cream contained 3％ of CC-516 improved skin hydration above 16.5％. Especially, the skin elasticity increases more than 35% and skin wrinkles decreased more than 23％. The CC-516 was designed to be utilized in cosmetology. The cream containing 3％ of this product has not only protecting effect on the skin mechanical properties provided by the collagen and the elastin in the derm but also restructuring effect of scarring or aging tissue.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.25-26
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• 2007

At the time when nanostructured materials (NSMs) are becoming a major focus of materials research, the attention of researchers is turning more to their mechanical performance. In contrast with conventional coarse grained materials, which are either strong or ductile, but rarely both at the same time, it is expected that with NSMs both high strength and ductility can be achieved and confirmed by several experimental studies. In spite of the significant interest and efforts in the mechanical properties of NSMs, deformation mechanisms during plastic deformation as well as elastic deformation are not well established yet. In this talk, the deformation mechanisms of NSMs under various grain sizes, temperatures and strain rates were investigated. It is based on recent modelling that appears to provide a conclusive description of the phenomenology and the mechanisms underlying the mechanical properties of NSMs. Based on the theoretical model that provides an adequate description of the grain size dependence of elasticity and plasticity covering all grain size range from coarse down to the nanoscale, the tensile deformation response of NSMs, especially focusing on the deformation mechanisms was investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.857-860
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• 2008

This study shows systematic procedures for investigating creep and shrinkage properties of 50, 60, 70 MPa concrete mixes, which were developed by Lotte E&C R&D Ins. for Lotte Super Tower Jamsil. The concrete test was performed both local and foreign laboratory, S-Lab. and CTL Group respectively. The former have done for total five days. The procedures included the followings, specimen fabrication, mold removal, specimen marking, water bath curing, packaging, and shipment. The latter has been doing by CTL within PCA(Portland Cement Association). They are testing on static and dynamic modulus of elasticity, compressive strength, creep & shrinkage, splitting tensile strength. In the case of creep and shrinkage, the test will be doing for 18 months according to each loading age.

• Journal of the Economic Geographical Society of Korea
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• v.17 no.3
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• pp.447-464
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• 2014

Creative industries are important due to the capability of enhancing urban competitiveness. This study is focused on unravelling the uneven growth and geographic distributions of creative industries. The main results are as follows. First, the primary city, Seoul, has too much eminence than the citysize rule suggests, and the creative-industry elasticity is very high compared to population and all industry. Second, Seoul is reinforcing the uneven growth with adjacent cities. Third, the local main cities have little power to enhance creative industries and the local small cities grow randomly. Fourth, each city should have more deliberation in accepting creative industries as an urban growth strategy.