• Geophysics and Geophysical Exploration
• /
• v.14 no.2
• /
• pp.127-132
• /
• 2011

We acquired and interpreted more than 650 km of high-resolution seismic reflection profiles in the Hupo Basin, offshore east coast of Korea at $37^{\circ}N$ in the East Sea (Japan Sea) to image shallow and basement deformation. The seismic profiles reveal that the main depocenter of the Hupo Basin in the study area is bounded by the large offset Hupo Fault on the east and an antithetic fault on the west; however, the antithetic fault is much smaller both in horizontal extension and in vertical displacement than the Hupo Fault. Sediment infill in the Hupo Basin consists of syn-rift (late Oligocene. early Miocene) and post-rift (middle Miocene.Holocene) units. The Hupo Fault and other faults newly defined in the Hupo Basin strike dominantly north and show a sense of normal displacement. Considering that the East Sea has been subjected to compression since the middle Miocene, we interpret that these normal faults were created during continental rifting in late Oligocene to early Miocene times. We suggest that the current ENE direction of maximum principal compressive stress observed in and around the Korean peninsula associated with the motion of the Amurian Plate induces the faults in the Hupo Basin to have reverse and right-lateral, strike-slip motion, when reactivated. A recent earthquake positioned on the Hupo Fault indicates that in the study area and possibly further in the eastern Korean margin, earthquakes would occur on the faults created during continental rifting in the Tertiary.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.29 no.4
• /
• pp.206-216
• /
• 2017

The temporal distribution of the turbulence kinetic energy (TKE) and the vertical component of Reynolds stresses ($-{\bar{u^{\prime}w^{\prime}}}$) was measured during one wave period under high wave energy conditions. The wave data were obtained at Hujeong Beach in the east coast of Korea at January 14~18 of 2017 when an extratropical cyclone was developed in the East Sea. Among the whole thousands of waves measured during the period, hundreds of regular waves that had with similar pattern were selected for the analysis in order to give three representing mean wave patterns using the ensemble average technique. The turbulence properties were then estimated based on the selected wave data. It is interesting to find out that $-{\bar{u^{\prime}w^{\prime}}}$ has one clear peak near the time of flow reversal while TKE has two peaks at the corresponding times of maximum cross-shore velocity magnitudes. The distinguished pattern of Reynolds stress indicates that vertical fluxes of such properties as suspended sediments may be enhanced at the time when the horizontal flow direction is reversed to disturb the flows, supporting the turbulence convection process proposed by Nielsen (1992). The characteristic patterns of turbulence properties are examined using the CADMAS-SURF Reynolds-Averaged Navier-Stokes (RANS) model. Although the model can reasonably simulate the distribution of TKE pattern, it fails to produce the $-{\bar{u^{\prime}w^{\prime}}}$ peak at the time of flow reversal, which indicates that the application of RANS model is limited in the prediction of some turbulence properties such as Reynolds stresses.

• Polymer(Korea)
• /
• v.25 no.3
• /
• pp.359-366
• /
• 2001

Isothermal physical aging of a glass fiber/epoxy composite was examined at different aging temperatures ($T_a$) and degrees of conversion (monitored by the glass transition temperature, $T_g$) by means of the TBA torsion pendulum technique. The range of aging temperature was from 10 to $130^{\circ}C$ : the conversion was systematically changed from $T_g$=$76^{\circ}C$ to $T_g$=$177^{\circ}C$ (fully crosslinked). The effect of isothermal physical aging was manifested as perturbations of the modulus and mechanical loss vs. temperature in the vicinity of $T_a$ for all conversions. The rate of isothermal physical aging determined from the change of modulus with aging time at fixed aging temperature decreased and then increased with increasing conversion below T$_{a}$=9$0^{\circ}C$. There exists a superposition in aging rate vs. ($T_g$ -$T_a$) by shifting horizontally and vertically. This implies that the physical aging process is independent of the change of chemical structure as conversion proceeds. It has been found that water absorbed at the aging temperature below $70^{\circ}C$ during isothermal physical aging lowers the apparent aging rate. It is due to the absorbed water molecules forming strong polar interactions with hydroxyl group on network chain and reducing the segmental mobility during the physical aging.g.

• The Journal of Korean Institute of Information Technology
• /
• v.16 no.11
• /
• pp.51-59
• /
• 2018

The Multi-Mission Unmanned Surface Vehicle(MMUSV), which is manufactured using glass Fiber Reinforced Plastic(FRP) material, is designed to perform a surveillance and reconnaissance on the sea. Various navigation sensors, such as RADAR, RIDAR, camera, are mounted on a mast to perform an autonomous navigation. And a dummy gun is mounted on the deck of the MMUSV for a target tracking and disposal. It is necessary to analyze a strength for structures mounted on the deck because the MMUSV performs missions under a severe sea state. In this paper, a strength analysis of the mast structure is performed on static loads and lateral external loads to verify an adequacy of the designed mast through a series of simulations. Based on the results of captive model tests, a strength analysis for a heave motion of the mast structure is conducted using a simulation tool. Also a simulation and fatigue test for a mounting part between the MMUSV and the dummy gun are performed using a specimen. The simulation and test results are represented that a structure of the mast and mounting part of the dummy gun are appropriately designed.he impact amount are performed through simulation and experiments.

• The Journal of Korean Academy of Prosthodontics
• /
• v.32 no.1
• /
• pp.120-147
• /
• 1994

This study was performed for the purpose of evaluating the stress distribution around threaded type implants, cylindrical type implants and teeth connected with rigid or non-rigid connector. The stress distribution around the surrounding bone was analyzed by three-dimensional photoelastic method. Twelve mandibular photoelastic epoxy resin models and a circular polariscope were used to record the isochromatic fringes. After the stress distribution around the implant and tooth was observed, the results were as follows ; 1. In threaded type implants, stress concentrated patterns were observed at the neck either vertical or 25 degree lateral force. 2. The stress concentrated patterns were observed at the tooth apical portion and neck portions of the implant and tooth when a threaded implant was connected with the tooth by either a rigid or non-rigid connector. More force was generated at the tooth neck portion by a rigid connector and more force at the implant neck portion by a non-rigid connector. 3. The stress concentrated patterns were observed at the apical portion of the implant and tooth when a cylindrical type ,implant was connected with the tooth either by a rigid or non-rigid connector. More force was generated at the tooth apical portion by a rigid connector and more force at the neck portion of the tooth and implant by a non-rigid connector. 4. The stress around the tooth was more equally distributed in a threaded type implant than in a cylindrical implant when the tooth was connected with either a rigid or non-rigid connector. 5. The stress around a threaded type implant was progressively more equally distributed in the following order : 1) when used a single implant, 2) a non-rigid connection with the implant and tooth, 3) a rigid connection with the implant and tooth, 4) a rigid connection with two implant fixtures.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.37 no.1
• /
• pp.12-22
• /
• 2019

This study derived the design aspects by carrying out the case study of Neunggok prehistoric remains park, Ansansingil historic park and Yongjuk historic park to which are taken measures to preserve undesignated cultural heritages after studying the related laws & regulations and the systems as the design conditions of historic park preserving buried cultural heritages. The results of the study are as follows. First, according to the laws & regulations related to the historical parks, the historic sites should be preserved and utilized at the same time and can have history-related facility spaces, squares, rest spaces, exercise spaces, education & culture space, and convenience spaces. Second, by the space organization and the circulation system emphasizing only the preservation of buried cultural heritages, the feature-preservation space and the functional space are separated and due to not accepting the usage behavior considering peripheral land use, the effectiveness of the historical park was low. Third, the passive feature-preservation methods such as the preservation of the exposed site in architectural methods, the reproduction of the dugout hut, and the planting Royal azaleas or displaying stone after covering up the location of the pit dwellings with soil and the usage mainly for viewing have weakened the identity of the historical park. Fourth, the fence preventing users' access interferes experiencing the features, and the vertical structure protecting the upper part of the exposed features has overwhelmed the landscape of the historical parks. Fifth, it was difficult to figure out the feature space only by the texts mainly on terminologies and the excavation photographs presented on the information signs which introduce the buried cultural heritages.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.5 no.1
• /
• pp.21-30
• /
• 1985

The tension leg platform (TLP) is a kind of compliant structures, and is also a type of moored stable platform with a buoyancy exceeding the weight because of having tensioned vertical anchor cables. In this paper, among the various kinds of tension leg structures, Deep Oil Technology (DOT) TLP was analyzed because it has large-displacement portions of the immersed surface such as vertical corner pontoons and small-diameter elongated members such as cross-bracing. It also has results of hydraulic model tests, comparable with theorectical analysis. Because of the vertical axes of symmetry in the three vertical buoyant legs and because there are no larger horizontal buoyant members between these three vertical members, it was decided to develop a numerical algorithm which would predict the dynamic response of the DOT TLP using the previously developed numerical algorithm Floating Vessel Response Simulation (FVRS) for vertically axisymmetric bodies of revolution. In addition, a linearized hydroelastic Morison equation subroutine would be developed to account for the hydrodynamic pressure forces on the small member cross bracing. Interaction between the large buoyant members or small member cross bracings is considered to be negligible and is not included in the analysis. The dynamic response of the DOT TLP in the surge mode is compared with the results of the TLP algorithm for various combinations of diffraction and Morison forces and moments. The results which include the Morison equation are better than the results for diffraction only. This is because the vertically axisymmetric buoyant members are only marginally large enough to consider diffractions effects. The prototype TLP results are expected to be more inertially dominated.