• Journal of Periodontal and Implant Science
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• v.36 no.2
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• pp.531-554
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• 2006

Oral implants must fulfill certain criteria arising from special demands of function, which include biocompatibility, adequate mechanical strength, optimum soft and hard tissue integration, and transmission of functional forces to bone within physiological limits. And one of the critical elements influencing the long-term uncompromise functioning of oral implants is load distribution at the implant- bone interface, Factors that affect the load transfer at the bone-implant interface include the type of loading, material properties of the implant and prosthesis, implant geometry, surface structure, quality and quantity of the surrounding bone, and nature of the bone-implant interface. To understand the biomechanical behavior of dental implants, validation of stress and strain measurements is required. The finite element analysis (FEA) has been applied to the dental implant field to predict stress distribution patterns in the implant-bone interface by comparison of various implant designs. This method offers the advantage of solving complex structural problems by dividing them into smaller and simpler interrelated sections by using mathematical techniques. The purpose of this study was to evaluate the stresses induced around the implants in bone using FEA, A 3D FEA computer software (SOLIDWORKS 2004, DASSO SYSTEM, France) was used for the analysis of clinical simulations. Two types (external and internal) of implants of 4.1 mm diameter, 12.0 mm length were buried in 4 types of bone modeled. Vertical and oblique forces of lOON were applied on the center of the abutment, and the values of von Mises equivalent stress at the implant-bone interface were computed. The results showed that von Mises stresses at the marginal. bone were higher under oblique load than under vertical load, and the stresses were higher at the lingual marginal bone than at the buccal marginal bone under oblique load. Under vertical and oblique load, the stress in type I, II, III bone was found to be the highest at the marginal bone and the lowest at the bone around apical portions of implant. Higher stresses occurred at the top of the crestal region and lower stresses occurred near the tip of the implant with greater thickness of the cortical shell while high stresses surrounded the fixture apex for type N. The stresses in the crestal region were higher in Model 2 than in Model 1, the stresses near the tip of the implant were higher in Model 1 than Model 2, and Model 2 showed more effective stress distribution than Model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.587-593
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• 2019

The field of geospatial information is rapidly changing due to the development of sensor and data processing technology that can acquire location information. And demand is increasing in various related industries and social activities. The construction and utilization of three dimensional geospatial information that is easy to understand and easy to understand can be an essential element to improve the quality and reliability of related services. In recent years, 3D laser scanners are widely used as 3D geospatial information construction technology. However, 3D laser scanners may cause shadow areas where data acquisition is not possible when objects are large in size or complex in shape. In this study, 3D model of an object has been created by acquiring oblique images using an unmanned aerial vehicle and processing the data. The study area was selected, oblique images were acquired using an unmanned aerial vehicle, and point cloud type 3D model with 0.02 m spacing was created through data processing. The accuracy of the 3D model was 0.19m and the average was 0.11m. In the future, if accuracy is evaluated according to shooting and data processing methods, and 3D model construction and accuracy evaluation and analysis according to camera types are performed, the accuracy of the 3D model will be improved. In the point cloud type 3D model, Cross section generation, drawing of objects, and so on, it is possible to improve work efficiency of spatial information service and related work.

• Wind and Structures
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• v.5 no.2_3_4
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• pp.337-346
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• 2002

Wind tunnel pressure measurements and numerical simulations based on the Reynolds Stress Model (RSM) are compared with full and model scale data in the flow area of impingement, separation and wake for $60^{\circ}$ and $90^{\circ}$ wind azimuth angles. The phase averaged fluctuating pressures simulated by the RSM model are combined with modelling of the small scale, random pressure field to produce the total, instantaneous pressures. Time averaged, rsm and peak pressure coefficients are consequently calculated. This numerical approach predicts slightly better the pressure field on the roof of the TTU (Texas Tech University) building when compared to the wind tunnel experimental results. However, it shows a deviation from both experimental data sets in the impingement and wake regions. The limitations of the RSM model in resolving the intermittent flow field associated with the corner vortex formation are discussed. Also, correlations between the largest roof suctions and the corner vortex "switching phenomena" are observed. It is inferred that the intermittency and short duration of this vortex switching might be related to both the wind tunnel and numerical simulation under-prediction of the peak roof suctions for oblique wind directions.

• Wind and Structures
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• v.6 no.3
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• pp.179-196
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• 2003

A long suspension bridge is often located within a unique wind environment, and strong winds at the site seldom attack the bridge at a right angle to its long axis. This paper thus investigates the buffeting response of long suspension bridges to skew winds. The conventional buffeting analysis in the frequency domain is first improved to take into account skew winds based on the quasi-steady theory and the oblique strip theory in conjunction with the finite element method and the pseudo-excitation method. The aerodynamic coefficients and flutter derivatives of the Tsing Ma suspension bridge deck under skew winds, which are required in the improved buffeting analysis, are then measured in a wind tunnel using specially designed test rigs. The field measurement data, which were recorded during Typhoon Sam in 1999 by the Wind And Structural Health Monitoring System (WASHMS) installed on the Tsing Ma Bridge, are analyzed to obtain both wind characteristics and buffeting responses. Finally, the field measured buffeting responses of the Tsing Ma Bridge are compared with those from the computer simulation using the improved method and the aerodynamic coefficients and flutter derivatives measured under skew winds. The comparison is found satisfactory in general.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.94-97
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• 2004

In this paper, we investigate fringe-field switching (FFS) mode cell by the ion beam (IB) alignment method on the a-C:H thin film, to analyze electro-optical characteristics in this cell. We studied on the suitable inorganic thin film for fringe-field switching (FFS) cell and the aligning capabilities of nematic liquid crystal (NLC) using the new alignment material of a-C:H thin film An excellent voltage-transmittance (V-T) and response time curve of the IB-aligned FFS-LCD was observed with oblique IB exposure on the DLC thin films. Also, AC V-T hysteresis characteristics of the IB-aligned FFS-LCD with IB exposure on the DLC thin films is almost the same as that of the rubbing-aligned FFS cell on a polyimide (PI) surface.

• Journal of the Korean Arthroscopy Society
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• v.12 no.2
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• pp.118-124
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• 2008

Purpose: Recent development and advances in the arthroscopic surgical techniques for anterior cruciate ligament(ACL) reconstruction have led to the ideal location for more oblique anatomic point of the femur from 10 to 10:30 o'clock(in the right knee) and from 2 to 1:30 o'clock(in the left knee) in the frontal plane. This study was performed to compare the operative methods and the radiologic results of the femoral tunnels made through the tibial tunnel(trans-tibial approach) and the anteromedial portal. Materials and Methods: From January 2003 to May 2004, on hundred reconstructions of ACL were performed. Group I(the femoral tunnel made through the tibial tunnel) consisted of 50 cases and group I(the femoral tunnel made through the anteromedial portal) consisted of 50 cases. The operative methods and the radiographic results of the femoral tunnels were compared. Results: Femoral tunnel was made more easily at more oblique anatomic point in group II than in group I. In group II, better visual field was achieved at the angle of 100? flexion of the knee joint, the risks of the posterior cortical breakage and the tunnel-graft mismatching were reduced more, and the divergence of femoral interference screw from the radiograph decreased more than in group I(p<0.05). The angle between the femoral tunnel and the longitudinal axis of ACL increased in group II. Conclusion: Anteromedial portal technique was useful for femoral tunneling toward 10 to 10:30 o'clock(in the right knee) and 2 to 1:30 o'clock(in the left knee) in ACL reconstruction. Level of Evidence:Level III, case-control study.

• Korean Institute of Interior Design Journal
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• v.22 no.1
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• pp.164-173
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• 2013

This study aims to analyze the aesthetic thought and expression tendency appeared in contemporary architecture by looking at today's architectural art based on the concept of the uncanny that Sigmund Freud contended as an aesthetic principle, of the aesthetic concepts tossed around to define the contemporary times in the aesthetics field and discuss the architectural analysis possibility of the concept of the uncanny. The generation structure of the uncanny that generates experiences of fear and surprise is classified into dual structure, trauma, threatening structure, and repetition compulsion. This is the principle that evokes a sense of experiencing subject, incorporates sensibility, and vitalizes internal process. This is also the methodology to organize and structure the concept of the uncanny. When seen from the four factors drawn from the concept of the uncanny and aesthetic expressions, the uncanny expression characteristics of contemporary architecture includes isolation, subversion, trace, absence, oblique line, flotation, concealment, and disturbance. Isolation and subversion refers to producing the space of the pressure of tension and relaxation caused by repression and relief from repression and eliciting the maximum expansion of the sense of space through spatial change. Trace and absence indicates being able to elicit more intense emotions from the experiencing subject by applying the images of alienation and absence in the way to reproduce historical trauma. This happens by implementing the potential value of physical activity. Oblique line and flotation means visual impulse. This happens in the way to visualize uneasy points. This causes uncanny by threatening the survival. Finally, concealment and disturbance refers to creating unpredictable space. The concept of masquerade and maze space composition are applied in the way to activate spatial perception, including space exploration and unintended subject's forced selection. As stated above, the uncanny expression characteristics shown in contemporary architecture can be presented as indicators that are available to analyze the undecided and diversified contemporary architecture aesthetically. In this respect, this study has great significance.

• Ocean and Polar Research
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• v.24 no.3
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• pp.179-187
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• 2002

The Ayu Trough, located in the southern end of the Philippine Sea, represents a divergent boundary between the Philippine Sea and the Caroline Plates. A detailed geophysical survey was carried out in the Ayu Trough by R/V Onnuri. Topographically, the Ayu Trough resembles an slow spreading ridge. The trough can be divided into three sections: the south $(0^{\circ}-1^{\circ}30'N),\;middle\;(1^{\circ}30'-4^{\circ}N)$, and north $(4^{\circ}-6^{\circ}30'N)$. The seafloor in the middle section is characterized by features asymmetric with respect to the axis. These features were probably produced by NW-SE and NNW-SSE extensions and seem to support the argument that the opening of the Ayu Trough occurred in an oblique fashion. Farther south, a long transform fault but with a short offset defines the boundary between middle and southern sections. The axial depth increases a stepwise to the south of $1^{\circ}30'N$. A clear difference can be seen between the southern and middle sections with the latter exhibiting much higher mantle Bouguer anomaly values in the axial region. The anomaly indicates that the axial crust perhaps experienced a much higher degree of extension in the middle than in the southern section. The analyses of magnetic field data reveal that the region beyond 100km exhibits considerable variations, whereas the magnetic anomalies within 100km from the trough axis are very much subdued. This observation suggests that the opening of the Ayu Trough involved an initial stage of rifting of existing volcanic arcs, followed by production of new seafloor.

• Computational Structural Engineering
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• v.9 no.2
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• pp.133-142
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• 1996

In this paper, two different techniques for mixed-mode type engineering fracture mechanics are investigated to estimate the stress intensity factors by using p-version finite element model. These two techniques are displacement extrapolation with COD and CSD method and J-integral with decomposition method. By decomposing the displacement field obtained from p-version of finite element analysis into symmetric and antisymmetric displacement fields with respect to the crack line, Mode-I and Mode-II stress intensity factors can be determined using aforementioned techniques. The example problems for validating the proposed techniques are centrally and centrally oblique cracked panels under tension. The numerical results associated with the variation of oblique angle and the ratio of crack length and panel width (a /W ratio) are compared with those by theoretical values and empirical solutions in literatures. Very good agreements with the existing solutions are shown.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.75-78
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• 2004

Various jet engines (Turbine engine family and RAM Jet engine) have been developed for high speed aircrafts. but their application to hypersonic flight is restricted by principle problems such as increase of total pressure loss and thermal stress. Therefore, the development of next generation propulsion system for hypersonic aircraft is a very important subject in the aerospace engineering field, SCRAM Jet engine based on a key technology, Supersonic Combustion. is supposed as the best choice for the hypersonic flight. Since Supersonic Combustion requires both rapid ignition and stable flame holding within supersonic air stream, much attention have to be given on the mixing state between air stream and fuel flow. However. the wider diffusion of fuel is expected with less total pressure loss in the supersonic air stream. So. in this study the direction of fuel injection is inclined 30 degree to downstream and the total pressure of jet is controlled for lower penetration height than thickness of boundary layer. Under these flow configuration both streams, fuel and supersonic air stream, would not mix enough. To spread fuel wider into supersonic air an aerodynamic force, baroclinic torque, is adopted. Baroclinic torque is generated by a spatial misalignment between pressure gradient (shock wave plane) and density gradient (mixing layer). A wedge is installed in downstream of injector orifice to induce an oblique shock. The schlieren optical visualization from side transparent wall and the total pressure measurement at exit cross section of combustor estimate how mixing is enhanced by the incidence of shock wave into supersonic boundary layer composed by fuel and air. In this study non-combustionable helium gas is injected with total pressure 0.66㎫ instead of flammable fuel to clarify mixing process. Mach number 1.8. total pressure O.5㎫, total temperature 288K are set up for supersonic air stream.