• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.1 s.256
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• pp.68-75
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• 2007

A three-dimensional computation is conducted to simulate a three-dimensional rotating stall in a low speed axial compressor. It is generally known that a tip leakage flow has an important role on a stall inception. However, almost of researchers have taken no interest in a role of the hub-comer-stall on the rotating stall even though it is a common feature of the flow in an axial compressor operating near stall and it has a large effect on the flows and loss characteristics. Using a time-accurate unsteady simulation, it is found that the hub-comer-stall may be a trigger to collapse the axisymmetric flows under high loads. An asymmetric disturbance is initially originated in the hub-comer-stall because separations are naturally unstable flow phenomena. Then this disturbance is transferred to the tip leakage flows from the hub-comer-stall and grows to be stationary stall cells, which adheres to blade passage and rotate at the same speed as the rotor. When stationary stall cells reach a critical size, these cells then move along the blade row and become a short-length-scale rotating stall. The rotational speed of stall cells quickly comes down to 79 percent of rotor so they rotate in the opposite direction to the rotor blades in the rotating frame.

• Geomechanics and Engineering
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• v.14 no.1
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• pp.71-81
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• 2018

Soils are mostly nonhomogeneous and anisotropic in nature. In this study, nonhomogeneity and anisotropy of soil are taken into consideration by assuming that the cohesion increases with depth linearly and also varies with respect to direction at a particular point. A three-dimensional rotational failure mechanism is adopted, and then a three-dimensional stability analysis of slope is carried out with the failure surface in the shape of a curvilinear cone in virtue of the limit analysis method. A quasistatic approach is used to develop stability charts in nonhomogeneous and anisotropic soils. One can easily read the safety factors from the charts without the need for iterative procedures for safety factors calculation. The charts are of practical importance to prevent a plane failure in excavation slope whether it is physically constrained or not. Then the most suitable location of piles within the reinforced slope in nonhomogeneous and anisotropic soils is explored, as well as the interactions of nonhomogeneous and anisotropic coefficients on pile reinforcement effects. The results indicate that piles are more effective when they are located between the middle and the crest of the slope, and the nonhomogeneous coefficient as well as the anisotropic coefficient will not only influence the most suitable location for piles but also affect the calculated safety factor of existing reinforced slope. In addition, the two coefficients will interact with each other on the effect on slope reinforcement.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.263-266
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• 1997

Three dimensional numerical model based on the finite element method(FEM) were developed to predict the mechanical behavior of hip implants. The purpose of this study is to investigate the stress distribution of two types of cementless total hip replacement femoral component -a straight stem and a curved stem, and to compare their effect on the stress shielding between two types by three dimensional finite element method. The authors analyzed von Mises stress in the cortex & stem and compared the stress between the straight and the curved stem. In comparison of stresses between two different design of femoral stem, there was 25% more decrease of stress in straight stem than curved stem in the medial cortex at proximal region. The straight stem had consistently much lower stresses than the curved stem throughout the whole medial cortex with maximum 70% reduction of stress. However, there was little change in stress between nature and 2 implanted femur throughout the lateral cortex. Stress of femoral stem was much higher in the straight stem than the curved stem up to 60%. The straight stem had more chance of stress shielding and a risk of fatigue fracture of the stem compared with the curved stem in noncement hip arthroplasty. In design of femoral stem still we have to consider to develop design to distribute more even stress on the proximal medial cortex.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.2
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• pp.241-249
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• 2013

Ethanolamine (ETA) is widely used for alkalinization of water in steam cycles of nuclear power plants with pressurized water reactor. When ETA contained wastewater was released, it could increase COD and T-N. The treatment of the COD and T-N from ETA wastewater was investigated using the GAC as particle electrodes in three-dimensional electrode reactor (TDE). This study evaluated the effectiveness of GAC as particle electrode using different packing ratio at 300 V. The results showed that GAC-TDE could reduce ETA much more efficiently than ZVI-TDE at the mass ratio of GAC to insulator, 1:2. Additionally, The effect of applied electric potential to COD and T-N reduction was investigated. The results showed the high COD, T-N reduction and current efficiency at the low electric potential. Using the GAC-TDE will provide a better ETA reduction with reducing electrical potential dissipation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.2
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• pp.203-211
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• 1998

A traditional method to produce three dimensional orthophoto map has been studied by digital photogrammetry which decides a height by digitally searching conjugate points on the stereo image. Many researches in digital photogrammetric field are still in progress to determine conjugate points automatically. In this study, we analyze the effect of accuracy of area-based image matching with changing eight types of target area size using four types of image pyramid. The result of image matching to each method compared with 1/5,000 digital mapping data. We decided a optimal size of target area on a percentage of image matching. Digital elevation model is generated by matching results and bundle method. As a result, three dimensional orthophoto map is made in terms of digital elevation model and orthophoto.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.3 s.153
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• pp.228-237
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• 2007

The flow characteristics around a horn-type rudder behind an operating propeller of a high-speed large container carrier are studied through a numerical method in fully wetted and cavitating flow conditions. The computations are carried out in a small scale ratio of 10.00(gap space=5mm) to consider the gap effects. The Reynolds averaged Navier-Stokes equation for a mixed fluid and vapor transport equation applying cavitation model are solved. The axisymmetry body-force distribution technique is utilized to simulate the flow behind an operating propeller. The gap flow, the three-dimensional flow separation, and the cavitation are the flow characteristics of a horn-type rudder. The pattern of three-dimensional flow separation is analyzed utilizing a topological rule. The various cavity positions predicted by CFD were shown to be very similar to rudder erosion positions in real ship rudder. The effect of a preventing cavitation device, a horizontal guide plate, is also investigated.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.93-96
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• 2001

Tactile display devices use an array of pins mounted in the form of a matrix to present three-dimensional shapes to the user by raising and lowering. With a denser matrix of mounted pins, it can be expected that shape identification will be become easier and the time required for identification will also become shorter, but that problems of difficulty in fabrication will arise. It is necessary to consider such trade-offs in the development of such devices. This study conducted experiments to study the effect of pin pitch on shape identification as Part of the fundamental investigation of this subject. The experiment used three tactile display devices with pin pitches of In, 2mm and 3mm for geometrical shape identification, with response time and rate of misidentification taken as the performance data. Surfaces, edgs and vertices of three-dimensional shapes were used as the shape primitives for displayed shapes and several of each type were selected for presentation. The results obtained revealed that performance has different relationships to pin pitch with different shape primitives.

• The korean journal of orthodontics
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• v.54 no.2
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• pp.108-116
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• 2024

Objective: A three-dimensional-printed individual titanium plate was applied for maxillary protraction to eliminate side effects and obtain the maximum skeletal effect. This study aimed to explore the stress distribution characteristics of sutures during maxillary protraction using individual titanium plates in various directions and locations. Methods: A protraction force of 500 g per side was applied at forward and downward angles between 0° and 60° with respect to the Frankfort horizontal plane, after which the titanium plate was moved 2 and 4 mm upward and downward, respectively. Changes in sutures with multiple protraction directions and various miniplate heights were quantified to analyze their impact on the maxillofacial bone. Results: Protraction angle of 0-30° with respect to the Frankfort horizontal plane exhibited a tendency for counterclockwise rotation in the maxilla. At a 40° protraction angle, translational motion was observed in the maxilla, whereas protraction angles of 50-60° tended to induce clockwise rotation in the maxilla. Enhanced protraction efficiency at the lower edge of the pyriform aperture was associated with increased height of individual titanium plates. Conclusions: Various protraction directions are suitable for patients with different types of vertical bone surfaces. Furthermore, when the titanium plate was positioned lower, the protraction force exhibited an increase.

• Journal of Distribution Science
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• v.17 no.9
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• pp.67-81
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• 2019

Purpose - The overarching aim of this study is to empirically test the effect of ex-post control mechanisms on multi-dimensional trust and channel performance in franchise systems. Although the franchise system is a vertical marketing channel based on trust between the franchisor and the franchisees, issues related to franchisee's opportunistic behavior have persisted and thus requires research into the effective control system of franchise headquarters. Research design, data, and methodology - In this study, data was collected from 150 franchises to identify the effect of two types of franchising headquarters' control system on the multi-dimensional trust and franchise channel outcome between franchisor and franchisee. To test the hypotheses intended to achieve this aim, structural equations modeling technique is utilized. Results - The results of this research reveal that among the two formal control systems studied (output and process control), output control positively and significantly affects multidimensional trust. Additionally, among the three dimensions of trust employed in this study, only expertise has a positive and significant effect on contract compliance. Equally, only expertise and integrity have a negative and significant effect on opportunistic behavior. Conclusions - The study provides managerial and theoretical insights into understanding ex-post control mechanisms, trust, compliance and opportunistic behaviors in franchise systems.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.971-974
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• 2012

The facilitated diffusion effect on protein-DNA binding is studied. A rigorous theoretical approach is presented to deal with the coupling between one-dimensional and three-dimensional diffusive motions. For a simplified model, the present approach can provide numerically exact results, which are confirmed by the lattice-based Monte Carlo simulations.