• The Journal of Korean Academy of Prosthodontics
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• v.44 no.4
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• pp.394-404
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• 2006

Statement of problem: A conventional 3-unit fixed partial denture design with a pontic between two retainers is the most commonly used. However in cases where the mental nerve is in close proximity to the second premolar, a cantilever design can be considered. As such, logical and scientific evidence is lacking for the number and position of implants to be placed for partially edentulous patients, and no clear-cut set of treatment principles currently exist. Purpose : The purpose of this study was to evaluate prognosis of implant-supported fixed partial dentures and to compare changes in bone level which may rise due to the different factors. Material and method : The present study examined radiographical marginal bone loss in patients treated with implant-supported fixed partial dentures (87 prostheses supported by 227 implants) and evaluated the influence of the span of the pontic, type of the opposing dentition. Clinical complications were studied using a retrospective method. Within the limitation of this study. the following result were drawn Result, 1. Seven of a total of 227 implants restored with fixed prostheses failed, resulting in a 96.9% success rate. 2. Complications encountered during recall appointments included dissolution of temporary luting agent (17 cases), porcelain fracture (8 cases), loosened screws (5 cases), gingival recession (4 cases), and gingival enlargement (1 case). 3. Marginal bone loss, 1 year after prosthesis placement, was significant(P<0.05) in the group that underwent bone grafting, however no difference in annual resorption rate was observed afterwards. 4. Marginal bono loss, 1 year post-placement, was greater in cantilever-type prostheses than in centric pontic protheses (P<0.05). 5. Marginal bone loss was more pronounced in posterior regions compared to anterior regions (P<0.05). 6. The degree of marginal bone loss was proportional to the length of the pontic (P<0.05). Conclusion: The success rate of implant-supported fixed partial dentures, including marginal bone loss, was satisfactory in the present study. Factors influencing marginal bone loss included whether bone graft was performed, location of the pontic (s), location of the surgical area in the arch pontic span. Long-term evaluation is necessary for implant-supported fixed partial dentures, as are further studies on the relationship between functional load and the number of implants to be placed.

• Journal of Acupuncture Research
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• v.21 no.6
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• pp.63-84
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• 2004

Objective & Methods : To study the effects of anti-cancer, anti-metastasis and immune response improvement of herbal-acupuncture with Eclipta prostrata diffusae herba infusion solution(ELP-HAS), we injected ELP-HAS into Chung-wan(CV12) of C57BL/6 mice implanted intravenously with B16-F10 melanoma. We have reached the following conclusion through the effect on the percentage of $CD25^+/CD4^+$, $CD8^+/CD3e^+$, $CD69^+/B220^+$, $NK1.1^+/CD3e^+$cells in mouse PBMCs, the effect on the pulmonary colony formation number, and the effect on MST(Median Survival Time) and ILS(Increase of Life Span) of C57BL/6 mice implanted intravenously with B16-F10 melanoma. Results : The results were obtained as follows : 1. In the experiment groups treated with ELP(Ecliptae Herba) Herbal acupuncture, the spleen cell proliferation in BALB/c mouse was significantly increased compared with control group. 2. In the experiment groups treated with ELP(Ecliptae Herba) Herbal acupuncture, the percentage of $CD25^+/CD4^+$, $CD8^+/CD3e^+$, $CD69^+/B220^+$, $NK1.1^+/CD3e^+$cells in C57BL/6 mouse PBMCs was increased compared with control group. 3. In the experiment groups treated with ELP(Ecliptae Herba) Herbal acupuncture, the pulmonary colony formation number of C57BL/6 mice implanted intravenously with B16-F10 melanoma was decreased significantly compared with control group. 4. In the experiment groups treated with ELP(Ecliptae Herba) Herbal acupuncture, MST(Median Survival Time) and ILS(Increase of Life Span) of C57BL/6 mice implanted intravenously with B16-F10 melanoma were increased significantly compared with control group. Conclusions : ELP Herbal acupuncture injection into Chung-wan(CV12) of C57BL/6 mice is considered to be effective in anti-cancer, anti-metastasis and immune response improvement.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.2
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• pp.153-161
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• 2021

This study analyzed the ripple effect of the demand-side support for start-up venture companies on the macro economy using Dynamic General Equilibrium model. In the model, start-up venture companies were expressed in a manner that distinguished between workers and entrepreneurs by applying the span of control in the Lucas(1978). As a result of the analysis, when the share of public procurement of start-up venture companies was increased from 5.7% to 10%, the actual production of start-up venture companies increased by about 46.17% and the number of venture companies increased by about 150%. In addition, it was analyzed that the number of jobs through venture companies increased by about 61.56%. In addition, it was found that the economic effect was greatly reduced when the start-up venture company was supported as a subsidy for the supply sector with the same amount as the public procurement support. This is interpreted as the fact that if the government implements the supply-side support policy, the expansion of supply causes the price of start-up venture companies to fall, reducing the effect of the support policy in half. Therefore, when supporting start-up venture companies, the government should make efforts to maximize the policy effect by expanding the demand-side support through public procurement and reducing the payment of simple subsidies to start-up venture companies.

• Journal of Korean Society of Disaster and Security
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• v.15 no.3
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• pp.79-88
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• 2022

Cable-supported bridges, as important large infrastructures, require a long-term and systematic maintenance strategy. In particular, various methods have been proposed to secure safety for the bridges, such as installing various types of sensor on members in the bridges, and setting management thresholds. It is evidently necessary to propose a strategic plan to efficiently manage increasing number of cable-supported bridges and data collected from a number of sensors. This study aims to develop an analysis tool that can automatically remove abnormal signals and calculate statistical results for the purpose of efficiently analyzing a wide range of data collected from a long span bridge measurement system. To develop the tool, basic information such as the types and quantity of sensors installed in long span bridges and signal characteristics of the collected data were analyzed. Thereafter, the Humpel filtering method was used to determine the presence or absence of an abnormality in the signal and then filtered. The statistical results with filtered data were shown. Finally, one cable-stayed bridge and one suspension bridge currently in use were chosen as the target bridges to verify the performance of the developed tool. Signal processing and statistical analysis with the tool were performed. The results are similar to the results reported in the existing work.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.5 s.39
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• pp.91-99
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• 2004

In general, stadium structure with long span has low inherent natural frequency. In the stadium structure, structural behavior similar to resonance can be occurred easily by spectator rhythmical movements of which exciting period is small comparatively. It is required to investigate the safety and the serviceability of stadium structure. Therefore, there exists a necessity for accurate vibration analysis. Accurate analysis of stadium structure subjected to dynamic load is required for economical construction and safe design of stadium structure. Stadium structure should be modeled by refined mesh for accurate vibration analysis. As the mesh of stadium structure is refined, the number of divided elements increases in numerical analysis. The number of node is increased and numerous computer memories or computational time are required. So it is very difficult to analyze refine model of stadium structures by using the commercial programs. It is possible to efficient vibration analysis of stadium structure by finite element modeling method using equivalent beam element proposed in this paper, because the number of nodes is decreased remarkably.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.8-19
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• 2016

This paper investigates the effects of inlet turbulence conditions and near-wall treatment methods on the heat transfer prediction of gas turbine vanes within the range of engine relevant turbulence conditions. The two near-wall treatment methods, the wall-function and low-Reynolds number method, were combined with the SST and ${\omega}RSM$ turbulence model. Additionally, the RNG $k-{\varepsilon}$, SSG RSM, and $SST_+{\gamma}-Re_{\theta}$ transition model were adopted for the purpose of comparison. All computations were conducted using a commercial CFD code, CFX, considering a three-dimensional, steady, compressible flow. The conjugate heat transfer method was applied to all simulation cases with internally cooled NASA turbine vanes. The CFD results at mid-span were compared with the measured data under different inlet turbulence conditions. In the SST solutions, on the pressure side, both the wall-function and low-Reynolds number method exhibited a reasonable agreement with the measured data. On the suction side, however, both wall-function and low-Reynolds number method failed to predict the variations of heat transfer coefficient and temperature caused by boundary layer flow transition. In the ${\omega}RSM$ results, the wall-function showed reasonable predictions for both the heat transfer coefficient and temperature variations including flow transition onset on suction side, but, low-Reynolds methods did not properly capture the variation of the heat transfer coefficient. The $SST_+{\gamma}-Re_{\theta}$ transition model showed variation of the heat transfer coefficient on the transition regions, but did not capture the proper transition onset location, and was found to be much more sensitive to the inlet turbulence length scale. Overall, the Reynolds stress model and wall function configuration showed the reasonable predictions in presented cases.

• Journal of Korean Society of Steel Construction
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• v.21 no.5
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• pp.493-503
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• 2009

Bridge redundancy is defined as the capability of a bridge to sustain loads after one of its main members incurs damage. It is affected by many parameters, including the number of girders, span length, girder height, internal supports, and secondary members. The present AASHTO and Korean Bridge design codes, however, define bridge redundancy only as the number of girders, and neither the evaluation method nor the required level of redundancy is given. This study presented a redundancy evaluation method for plate girder bridges with severe fatigue damage based on the reliability method,by considering the essential parameters. A required level of redundancy was also proposed as a target system reliability index from the load capacity analysis and reliability analysis of the basis bridge designed by LRFD. Finally, the level of redundancy of simple and continuous plate girder bridges with a variable number of girders designed by ASD was evaluated and presented.

• Journal of the Korean Operations Research and Management Science Society
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• v.40 no.4
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• pp.83-105
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• 2015

Taxi, one of the passenger services, is an essential transportation system in our society. In spite of the importance of taxi service, deterioration of the service quality is continuously reported. In particular, taxi service failures due to traffic accidents have emerged as the most serious social problem which may incur a considerable amount of social costs. In this study, we focus on analyzing the causes of service quality deterioration-traffic accidents of both corporately owned and privately owned taxies in Seoul. The research objective is to find out the determinants of service quality deterioration of Taxi industry and to suggest policies for improving the taxi service in Seoul. We collected the archival data from KTSA (Korea Transportation Safety Authority) and ODP (Open Data Portal), which span from 2005 to 2014. Hierarchical regression analyses and a set of mediation tests are conducted. The root factors inducing traffic accidents of taxies are divided into competitive, and profitability factors. The statistical results indicate that the accident ratio per taxi is not only affected by competitive/profitability factors such as number of active taxi drivers, number of bus passengers, and taxi fare, but also mediated by the traffic violation ratio. To alleviate the current problems with taxi service in Seoul, we conclude that the number of taxies be reduced and the taxi fare be increased. Finally, we suggest several policies to improve the endemic taxi industry problems, over-supply and the low profitability by enhancing the linkage between service quality and profitability.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.3
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• pp.529-561
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• 2014

The two-phase turbulent flow past an interface-piercing circular cylinder is studied using a high-fidelity orthogonal curvilinear grid solver with a Lagrangian dynamic subgrid-scale model for large-eddy simulation and a coupled level set and volume of fluid method for air-water interface tracking. The simulations cover the sub-critical and critical and post critical regimes of the Reynolds and sub and super-critical Froude numbers in order to investigate the effect of both dimensionless parameters on the flow. Significant changes in flow features near the air-water interface were observed as the Reynolds number was increased from the sub-critical to the critical regime. The interface makes the separation point near the interface much delayed for all Reynolds numbers. The separation region at intermediate depths is remarkably reduced for the critical Reynolds number regime. The deep flow resembles the single-phase turbulent flow past a circular cylinder, but includes the effect of the free-surface and the limited span length for sub-critical Reynolds numbers. At different Froude numbers, the air-water interface exhibits significantly changed structures, including breaking bow waves with splashes and bubbles at high Froude numbers. Instantaneous and mean flow features such as interface structures, vortex shedding, Reynolds stresses, and vorticity transport are also analyzed. The results are compared with reference experimental data available in the literature. The deep flow is also compared with the single-phase turbulent flow past a circular cylinder in the similar ranges of Reynolds numbers. Discussion is provided concerning the limitations of the current simulations and available experimental data along with future research.

• The korean journal of orthodontics
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• v.29 no.6 s.77
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• pp.673-688
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• 1999

This study was conducted in order to analyze the mechanical characteristics of multiloop edgewise archwire (MEAW). The purposes were 1) to compare load deflection rate (LDR) of MEAW with that of various other arch wires in the individual interbracket span, 2) to compare the wire stiffness in the interbracket span with that in the multi-L-loop region (the span from distal border of the bracket of the lateral incisor to the mesial border of the buccal tube of the second molar), and 3) to verify the experimental results with theoretically derived formula. The single L-loops of five different horizontal lengths and multi-L-loops for the upper and lower arches were made out of .$016\times.022$ permachrome stainless steel wire. Straight segment of plain stainless steel, TMA and NiTi wire of the same dimension were prepared. The LDR was measured using Instron model 4466 with the load cell of 50N capacity at cross head speed of 1.0mm/min, and maximum deflection of 1.0mm. Five specimens were tested under each experimental condition. The wire stiffness number for each interbracket region and multi-L-loop region was calculated from the LDR and the interbracket spans. By dividing the theoretical model of multi-L-loop into 35 linear segments, the energy stored in each segment was obtained. Then the LDR and wire stiffness of single L-loop and multi-L-loop were calculated and compared. The findings were as follows : 1) The average LDR of MEAW in the individual interbracket region was 1/1.53 of that of the NiTi,1/2.47 of TMA and 1/5.16 of the plain stainless steel wire. 2) The wire stiffness of MEAW in the multi-L-loop region was 1.53 times larger than that in the interbracket region, and the LDR was almost twice as large as that of NiTi in that region. 3) According to the theoretically derived equation, the wire stiffness of the single L-loop was lower than that of multi-L-loop. The results of this study suggest that MEAW has the unique mechanical Property which could allow individual tooth movement and transmit elastic force effectively through the entire arch wire.