• Journal of Ocean Engineering and Technology
• /
• v.9 no.2
• /
• pp.156-166
• /
• 1995

Regrading the development of offshore natural gas field near Sakhalin Island which is an ice-infested area, this study aims to estimate the dynamic ice load for construction of offshore structures operating in this region. In this paper the design ice load and dynamic responses of a slender Arctic structure upon continuous ice movement are sutdied. Crushing agter a certain elastic deformation is assumed as a primary failure mechanism at the contact zone between semi-infinite level ice edge and the face of structure. Dynamic interaction forces are calculated using a modified Korzhavin's equation and a two-dimensional ice-structure interaction model is adopted. To verify the numerical model, dynamic analysis is performed for on of the Baltic Sea channel markers whose response patterns were presiously observed.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.326-326
• /
• 2016

The fault can be defined, in a geological context, as a rupture plane showing a significant displacement generated in the case that the local tectonic stress exceeds a threshold of rupture along a particular plane in a rock mass. The hydrogeological properties of this fault can be varied with the spatial distribution and the connectivity of void spaces in a fault. When the formation of fault includes the process of the creation and the destruction of void spaces, a complex relation between the displacement along the fault and the variation of void spaces. In this study, the variation of flow with the geometrical characteristics of the fault is simulated and analyzed by using the three-dimensional discrete fracture network model. Three different geometrical characteristics of the faults are considered in this study: 1) simple hydraulic conductive plane, 2) damaged zone, and 3) relay structure of faults.

• The Journal of Engineering Geology
• /
• v.26 no.1
• /
• pp.87-99
• /
• 2016

We present the results of two-dimensional numerical simulations predicting the flow of groundwater in a fractured unsaturated zone. We applied the k-field distribution of permeability derived from discrete fracture network (DFN) modeling as the hydraulic properties of a model domain. To model an unsaturated zone, we set the depth from the ground surface to the underground aquifer. The rate of water infiltration into the unsaturated zone was divided into two parts, an artificial structure surface and unsaturated soil zone. The movement of groundwater through the unsaturated zone was simulated with particular emphasis on contaminant transport. It was clearly observed that the contaminants dissolved in groundwater transported vertically from the ground surface to the saturated zone.

• Journal of Korean Academy of Nursing Administration
• /
• v.6 no.1
• /
• pp.147-159
• /
• 2000

This paper studied the factors that influence on RN staffing level in the 43 Specialized general hospitals. Market structure was analysed using the monopsony model. The degree of competition was estimated by Herfindal Index and market was defined as Great medical zone. As the result of the estimation, in the more competitive hospital market hospitals employed the higher level of RN staffing, so monopsony model was supported. Hospitals with above 1001bed employed more RN than hospitals with below 700bed did. Hospital type, hospital union and the number of medical doctor did not affect the level of RN staffing. There was positive correlation between the level of RN staffing and the number of nurse's aid. The structure of RN market in Specified general hospitals was proved monopsony market, it seems that government regulation will be needed to improve social efficiency and equity.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1996.04a
• /
• pp.253-257
• /
• 1996

A basic assumption in the current design and analysis of reinforced concrete(RC) box structures, which are constructed by the open cut and fill method, is that the displacements and forces are uniform in the longitudinal direction of the structure. The solution may be therefore obtatined from the analysis of a unit wide strip along longitudinal axis. This strip is said to be in a plane strain condition, meaning that the out of plane deformations are vanished. The current design of box structure is carried out by the result of planar frame model for the sake of simplicity. The purpose of this study is to show more rational design method of box culverts considering a rigid zone of corner joints. The current analysis of box structures will be compared with the plane strain analysis as well as 3-d shell model. Reinforcement quantity is also determined to resist the tensile force in corner joints of box structures using strut-tie model which has been developed through the elastic analysis.

• The Journal of Engineering Geology
• /
• v.8 no.3
• /
• pp.285-296
• /
• 1998

As a part of the study for understanding the deep geological structure of the Ogcheon Zone, both gravity and geomagnetic surveys are performed. A 70km survey line of which direction is nearly perpendicular to major faults in the southern tip of the Zone. The observed data are corrected and transformed into Bouguer and total magnetic intensity anomalies, respectively. Recent studies for petrology and geochemistry in the southwestern Ogcheon Zone in the vicinity of the survey line are reviewed for better interpretation. Both gravity and geomagnetic anomalies abruptly change around Janghung area, the southern boundary of the, Ogcheon Zone. This rapid increase of Bouguer anomaly around Janghung area can be explained by a deep seated normal fault with fairy large displacement between Precambrian gneisses and the denser intermediate plutonic rocks. It is believed that the fault acted an important role for the formation and evolution of the Ogcheon Zone. A pseudomagnetic intensity anomaly is calculated from the Bouguer anomaly assuming that the both anomalies are associated with the common source. From the origin of the survey line to the 50km point, the calculated anomaly coincides with observed magnetic anomaly. Whereas both anomalies show negative correlation in the outside 50km. From the residual Bouguer anomalies, the subterranean geological structure is provided through the iterative forward method. The initial model is obtained from informations about the surface geology as well as the results of the inverse method.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.25 no.12
• /
• pp.1618-1624
• /
• 1988

In this paper, a robust discrete model reference adaptive controller is proposed using a generalized model reference adaptive algorithm for single-input single-output discrete systems. A signal dependent time-varying dead-zone is employed in a generalized adaptive control structure. This adaptive controller is shown to assure the boundedness of the signals of the system even in the presence of bounded external disturbance.

• Smart Structures and Systems
• /
• v.28 no.6
• /
• pp.745-760
• /
• 2021

Dynamic buckling of structure is one of the failure modes that needs to be considered since it may result in catastrophic failure of the structure in a short period of time. For a thin fiber-reinforced polymer (FRP) plate under compression, buckling is an inherent hazard which will be intensified by the existence of defects like holes, cracks, and delamination. On the other hand, the growth of the delamination is another prime concern for thin FRP plates. In the current paper, reinforcing the plates against buckling is realized by using SMA wires in the form of stitches. A numerical framework is proposed to simulate the dynamic instability emphasizing the effect of the SMA stitches in suppressing delamination growth. The suggested algorithm is more accurate than the other methods when considering the transformation point of the SMA wires and the modeling of the cohesive zone using simple and yet reliable technique. The computational design of the method by producing the line by line orders leads to a simple algorithm for simulating the super-elastic behavior. The Lagoudas constitutive model of the SMA material is implemented in the form of user material subroutines (VUMAT). The normal bilinear spring model is used to reproduce the cohesive zone behavior. The nonlinear finite element formulation is programmed into FORTRAN using the Newmark-beta numerical time-integration approach. The obtained results are compared with the results obtained by the finite element method using ABAQUS/Explicit solver. The obtained results by the proposed algorithm and those by ABAQUS are in good agreement.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2000.10a
• /
• pp.222-229
• /
• 2000

The purpose of this study is to evaluate and make a comparison between the Ordinary Moment Resisting Frames using different analytical joint model for the Nonlinear response. For this purpose, 3-story structure was designed according to NEHRP 1994 Guidelines. And the center-line dimension model and model considering panel zone were used as analytical model for the structure. Nonlinear Static Procedure and Nonlinear Dynamic Procedure were used to evaluate seismic capacities and demands. The limitation in FEMA 273 was used as the variable number to predicte seismic demands of OMRFs. This analytical studies were performed with DRAIN-2DX modified by Shan Shi. Using the above results, the performance evaluation and seismic demands of OMRFs shall be performed. Finally NSP and NDP shall be compared.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.9 no.2
• /
• pp.209-218
• /
• 2017

Sea ice is the main factor affecting the safety of the Arctic engineering. However, traditional numerical methods derived from classical continuum mechanics have difficulties in resolving discontinuous problems like ice damage. In this paper, a non-local, meshfree numerical method called "peridynamics", which is based on integral form, was applied to simulate the interaction between level ice and a cylindrical, vertical, rigid structure at different velocities. Ice in the simulation was freshwater ice and simplified as elastic-brittle material with a linear elastic constitutive model and critical equivalent strain criterion for material failure in state-based peridynamics. The ice forces obtained from peridynamic simulation are in the same order as experimental data. Numerical visualization shows advantages of applying peridynamics on ice damage. To study the repetitive nature of ice force, damage zone lengths of crushing failure were computed and conclude that damage zone lengths are 0.15-0.2 times as ice thickness.