• Journal of the Korean Geotechnical Society
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• v.32 no.9
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• pp.51-62
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• 2016

Parametric studies for various site conditions by using 3d numerical model were carried out in order to estimate dynamic behavior of soil-pile-structure system in dry soil deposits. Proposed model was analyzed in time domain using FLAC3D which is commercial finite difference code to properly simulate nonlinear response of soil under strong earthquake. Mohr-Coulomb criterion was adopted as soil constitutive model. Soil nonlinearity was considered by adopting the hysteretic damping model, and an interface model which can simulate separation and slip between soil and pile was adopted. Simplified continuum modeling was used as boundary condition to reduce analysis time. Also, initial shear modulus and yield depth were appropriately determined for accurate simulation of system's nonlinear behavior. Parametric study was performed by varying weight of superstructure, pile length, pile head fixity, soil relative density with proposed numerical model. From the results of parametric study, it is identified that inertial force induced by superstructure is dominant on dynamic behavior of soil-pile-structure system and effect of kinematic force induced by soil movement was relatively small. Difference in dynamic behavior according to the pile length and pile head fixity was also numerically investigated.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.1
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• pp.13-23
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• 2008

In coastal region, eutrophication, Do deficit and red tide are frequently occurred by influx of fresh water. When the fresh water containing pollutants is discharged into the sea, the surrounding water is contaminated by dispersion of freshwater flowing into coastal waters. The prediction and analysis about the dispersion process of the discharged fresh water should be conducted. A modeling system using GUI was developed to simulate hydrodynamic flow and fresh water dispersion in coastal waters and to analyze the results efficiently. The modeling module of the system includes a tide model using a finite element method and a fresh water dispersion model using a particle-tracking method. This system was applied to predict the tidal currents and fresh water dispersion in Mokpo coastal zone. To verify accuracy of the hydrodynamic model, the simulation results were compared with observed sea level and time variations of tidal currents showing a good agreement. The fresh water dispersion was verified with observed salinity distribution. The dispersion model also was verified with analytic solutions with advection-diffusion problems in 1-dimensional and 2-dimensional simple domain. The system is operated on GUI environment, to ease the model handling such as inputting data and displaying results. Therefore, anyone can use the system conveniently and observe easily and accurately the simulation results by using graphic functions included in the system. This system can be used widely to decrease the environmental disaster induced by inflow of fresh water into coastal waters.

• Journal of Biomedical Engineering Research
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• v.20 no.1
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• pp.37-44
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• 1999

Because of bone resorption, wear of ultra-high molecular weight polyethylene(UHMWPE) in total knee arthroplasty has been recognized as a major factor in long-term failure of knee implant. The surface damage and the following harmful wear debris of UHMWPE is largely related to contact stress. Most of the previous studies focused on the contact condition only at the articulating surface of UHMWPE. Recently, contact stress at the metal-backing interface has been implicated as one of major factors in UHMWPE wear. Therefore, the purpose of the is study is to investigate the effect of the contact stress for different thickness, conformity friction coefficient, and flexion degree of the UHMWPE component in total knee system, considering the contact conditions at both interfaces. In this study, a two-dimensional non-linear plane strain finite element model was developed. The results showed that the maximum value of von-Mises stress occurred below the articulating surface and the contact stress was lower for the more conforming models. All-polyethylene component showed lower stress distribution than the metal-backed component. With increased friction coefficient on the tibiofemoral contact surface, the maximum shear stress increased about twofold.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.55-68
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• 2020

In order to investigate the hydraulic characteristics of a boundary layer streaming over the beach cusps appeared in swells prevailing mild seas, we numerically simulated the shoaling process of Edge waves over the beach cusp. Synchronous Edge waves known to sustain the beach cusps could successfully be duplicated by generating two obliquely colliding Edge waves in front of beach cusps. The amplitude A_B and length L_B of Beach Cusp were elected to be 1.25 m and 18 m, respectively based on the measured data along the Mang-Bang beach. Numerical results show that boundary layer streaming was formed at every phase of shoaling process without exception, and the maximum boundary layer streaming was observed to occur at the crest of sand bar. In RUN 1 where the shortest waves were deployed, the maximum boundary layer streaming was observed to be around 0.32 m/s, which far exceeds the amplitude of free stream by two times. It is also noted that the maximum boundary layer streaming mentioned above greatly differs from the analytical solution by Longuet-Higgins (1957) based on wave Reynolds stress. In doing so, we also identify the recovery procedure of natural beaches in swells prevailing mild seas, which can be summarized such as: as the infra-gravity waves formed in swells by the resonance wave-wave interaction arrives near the breaking line, the sediments ascending near the free surface by the Phase II waves orbital motion were carried toward the pinnacle of foreshore by the shoreward flow commenced at the steep front of breaking waves, and were deposited near the pinnacle of foreshore due to the infiltration.

• Economic and Environmental Geology
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• v.42 no.1
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• pp.27-53
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• 2009

A 30-m-thick Middle Ordovician Jigunsan Shale exposed along the southern limb of the Backunsan (Baekunsan) Syncline, Taebacksan (Taebaeksan) basin, has been simply considered as a transgressive shale sequence onlapped the underlying Maggol platform carbonates. Results of this study, however, suggest that majority of the Jigunsan Shale be interpreted as a regressive shale sequence downlapped onto a thin (ca. 240 cm) marine stratigraphic unit consisting of organic-rich (>3 wt.% of TOC) black shales in the lower Jigunsan Shale, which was accumulated at the time of maximum regional transgression. Detailed stratigraphic analysis in conjunction with XRD, XRF, and ICP-MS as well as Rock-Eval pyrolysis allows the thin marine stratigraphic unit in the Jigunsan Shale to define a condensed section that was deposited in a distinctive euxinic zone formed due to expansion of pycnocline during the early highstand phase. As well, a number of stratigraphic horizons of distinctive character that may have sequence stratigraphic or environmental significance, such as transgressive surface, maximum flooding surface, maximum sediment starvation surface, and downlap surface, are identified in the lower Jigunsan Shale. In the future, these stratigraphic horizons will provide very useful information to make a coherent regional stratigraphic correlation of the Middle Ordovician strata and to develop a comprehensive understanding on stratigraphic response to tectonic evolution as well as basin history of the Taebacksan Basin.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.481-495
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• 2020

After the resonator on the basis of the wave-filter theory was designed to control the waves with a specific frequency range surging into the harbor, the several case with the use of resonator have been reported in some part of sea, including the port of Long Beach, USA, and yacht harbor at Rome, Italy in order to control the long-period wave motion from the vessels. Recently, the utility and applicability of the resonator has been sufficiently verified in respect of the control of tsunami approximated as the solitary wave and/or the super long-period waves. However, the case with the application of tsunami in the real sea have not been reported yet. In this research, the respective case with the use of existing resonator at the port of Mukho and Imwon located in the eastern coast of South Korea were studied by using the numerical analysis through the COMCOT model adapting the reduction rate of 1983 Central East Sea tsunami and 1993 Hokkaido Southwest off tsunami. Consequently, the effectiveness of resonator against tsunami in the real sea was confirmed through the reduction rate of maximum 40~50% at the port of Mukho, and maximum 21% at the port of Imwom, respectively. In addition, it was concluded that it is necessary to study about the various case with application of different shape, arrangement, and size of resonator in order to design the optimal resonator considering the site condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.593-601
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• 2021

The axial fan is an element of a blower used for ventilation in various industrial fields. Many studies on aerodynamic performance have been conducted to assess axial fans using fluid dynamics. The subject was a large axial fan size, 1800 mm in diameter with 100 horsepower. The blower's axial fan consisted of blades, hubs, hub caps, and bosses are important components. The blade design has a great influence on the aerodynamic performance. 3D point data is extracted using an aerodynamic performance prediction program, and a 3D modeling shape is generated. The blades and hubs, which are important components, can be easily modified if processed by cutting owing to the environment in which blades and hubs are manufactured through die casting or gravity casting. In this study, the structural safety of components and the analysis results of weak areas at the rated operating speed of the axial fan were verified using the maximum stress and safety factor. The tip clearance reflected in the design was the rotation of the blade. To check whether there is interference with other components, the displacement result was derived to verify the structural safety of the axial fan.

• The Journal of Korean Philosophical History
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• no.50
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• pp.113-138
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• 2016

The purpose of this research is to establish the foundation for understanding the appearance of development, inheritance and acceptance of Toegye Yi Hwang(退溪李滉, 1501~1570)'s theory after his life by examining Udam Jeong Sihan(愚潭 丁時翰, 1625~1707)'s view on the Ido-seol(理到說), the Toegye's latter theory. After Toegye, Ido-seol was translated as 'The principle of matters reaches the human mind'. Galam Yi Hyunil(葛庵 李玄逸, 1627~1704), the contemporary scholar with Udam, criticized this translation for applying the directivity and motility to 'Li', the immovable principle. However, Udam agreed with the conventional interpretation of Ido-seol and understood it as the consilience of mind which got the entire principle(體) of 'Li(理)' and contained the application(用) of all things. He extended this concept as the level of 'sameness between objects and self [物我爲一]' based on his former theory, the exquisite interpretation of 'application of Li'. The meaning of 'sameness between objects and self[物我爲一]' is not amalgamation but applepie order of matter's principle in mind. The Udam's viewpoint is differ from Galam who tried to overcome the structural limit of Ido-seol by transforming 'Do(到)', the predicate of 'Ido(理到)', into 'Jin(盡)'. It means that he tried to interpret 'Ido(理到)' on the more essential aspect. His view can be the useful tool for understanding the Toegye's neo-Confucianism system with 'Li(理)' as central figure. It suggested that Udam's theory of the principle and the applecation of 'Li' can be the important theory to investigate the formation of Toegye schools' though and its development.

• The Journal of Korean Philosophical History
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• no.37
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• pp.47-70
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• 2013

The purpose of this paper is to figure out T'oegye's philosophy and its characteristics in comparison with Zhuzi's. T'oegye is well-known as the representative of Neo-confucianism in Korea. But his posterior scholars and even contemporary scholars have various viewpoints about his philosophy. So they give him some different evaluation. After Zhuzi's death 300 years later, T'oegye has accepted Zhuzi's philopophical thoughts. In addition, he has added his own philosophical insights on them. First, he indicates concretely the metaphysical activity of li through lidong that Zhuzi has mentioned in some measure. Second, under the ontological aspect of li, he explains that Four beginnings come from li. It implies that li manifests and qi follows. Finally he points out lidao--i.e. li manifests itself, about wuge in his epistemology. Here we can say that whatever his metaphysics/the theory of mind and heart, and epistemology, the whole system of T'oegye's philosophy has its theoretical coherence. He has succeeded Zhuzi's philopophical thoughts thoroughly and furthermore developed Neo-confucian theory in East Asia that has not made before.

• The Journal of Korean Philosophical History
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• no.30
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• pp.311-344
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• 2010

Over 100 years in Mainland China, the 'traditional' thought and culture have been transformed from 'the past must be sublated' to 'the heritage must be preserved.' Today, China hopes to deal with the negative effects of industrial development such as the gap between rich and poor, and the absence of common values etc. through the reconstruction of traditional thought and culture, especially that of Confucianism. The Chinese government superficially accepts Confucianism for the purpose of the social stabilization and ongoing economic development while they keep the Socialism as the nation's ideological system. In the private sectors, there is endeavoring move to make the Chinese traditional thought and culture global paralleled to their economic growth. There are also scholars who find the cultural unification and the spiritual comfort from the restoration of the traditional thought and culture. They, so called 'the critical successionists' or 'the cultural conservativists,' believe that the traditional thought and culture could play a role in the Chinese modernization, and the new understanding and interpretation of their tradition could provide an alternative for their future. In my view, we need a careful survey on the view of the critical successionists or the cultural conservativists who regard tradition and culture as a power (力量). With this, we are required to investigate our own problems through the new understanding of our traditional thought and culture.