• Maxillofacial Plastic and Reconstructive Surgery
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• v.36 no.3
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• pp.116-123
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• 2014

Purpose: The purpose of this study was to evaluate risks for wound dehiscence after guided bone regeneration (GBR) in dental implant surgery. Methods: Patients who received dental implant therapy with GBR procedure at Seoul National University Bundang Hospital (Seongnam, Korea) from June 2004 to May 2007 were included. The clinical outcome of interest was complications related to dental implant surgery. The factors influencing wound dehiscence, classified into patient-related factors, surgery-related factors and material-related factors, were evaluated. Results: One hundred and fifteen cases (202 implants) were included in this study. Wound dehiscence (19.1%) was considered a major complication. The risk of wound dehiscence was higher in males than in females (odds ratio=4.279, P =0.014). In the main graft, the allogenic group had the lowest risk of wound dehiscence (odds ratio=0.106, P =0.006). Though the external connection group had a higher risk of wound dehiscence than the internal connection group (odds ratio=2.381), the difference was not significant (P =0.100). Conclusion: In this study, male gender and main graft have the highest risk of wound dehiscence. To reduce wound dehiscence after GBR, instructions on postoperative care with supplementary procedure for the protection of the wound dehiscence is recommended, especially to male patients. A main graft with a gel base can reduce the risk of wound dehiscence.

• Structural Engineering and Mechanics
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• v.72 no.4
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• pp.479-489
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• 2019

The corrosion of reinforcement leads to a gradual decay of structural strength and durability. Several models for crack occurrence prediction and crack width propagation are investigated in this paper. Analytical and experimental models were used to predict the bond strength in the period of corrosion propagation. The manner of flexural strength loss is calculated by application of these models for different scenarios. As a new approach, the variation of the concrete beam neutral axis height has been evaluated, which shows a reduction in the neutral axis height for the scenarios without loss of bond. Alternatively, an increase of the neutral axis height was observed for the scenarios including bond and concrete section loss. The statistical properties of the parameters influencing the strength have been deliberated associated with obtaining the time-dependent bending strength during corrosion propagation, using Monte Carlo (MC) random sampling method. Results showed that the ultimate strain in concrete decreases significantly as a consequence of the bond strength reduction during the corrosion process, when the section reaches to its final limit. Therefore, such sections are likely to show brittle behavior.

• Wind and Structures
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• v.36 no.1
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• pp.41-60
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• 2023

The effect of cladding panel size on the size reduction factor (SRF) of extreme area-averaging wind pressure (EAWP) on the facades of a high-rise building is often ignored in previous studies. Based on wind tunnel tests, this study investigated the horizontal and vertical correlations of wind pressure on the facade claddings of square-section high-rise buildings. Then, the influencing parameters on the SRF of the EAWP on the cladding panels were analyzed, which were the panel area, panel width, panel length and building width. The results show clear regional distinctions in the correlation of wind pressures on the building facades and the rules of the horizontal and vertical correlations are remarkably different, which causes the cladding size ratio to impact the SRF significantly. Therefore, this study suggests the use of the non-dimensional comprehensive size parameter b^𝜶h^1-𝜶/B (𝜶 is the fitting parameter) determined by the cladding panel horizontal size b, cladding panel vertical size h and the building width B rather than the cladding panel area to describe the variation of the EAWP. Finally, some empirical formula for the SRF of the EAWP on the cladding of a high-rise building is proposed with the nondimensional comprehensive size parameter.

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.5
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• pp.495-498
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• 1995

Records taken on 372 young beef bulls tested at the Ellerslie Bull Test Station, Alberta, Canada from November 1981 to April 1987 were analyzed to quantify the effects of age of dam, on-test age, on-test liveweight and herd of origin of bull on feed efficiency (feed/gain, kg/kg) in the test period (n = 231) and ultrasonic measurement of bakcfat thickness (mm) at the end of the test (n = 372). The reduction in $R^2$ due to each influencing factor (i.e. the variation accounted for by the factor) was used to indicate the importance of the influencing factor. Age of dam and on-test age of bull were not important factors on feed/gain and ultrasonic backfat thickness, as they accounted for less than 0.5% of the variation in feed/gain and ultrasonic backfat thickness, respectively (p > 0.1). On-test liveweight had some influence on feed/gain and ultrasonic backfat thickness, accounting for 3.5% (p < 0.01) and 0.4% (p < 0.05) of the total variation, respectively. The regression coefficients of feed/gain and ultrasonic backfat thickness on on-test liveweight were 0.016 (kg/kg)/kg and .013 mm/kg, respectively, both being significant (p < 0.05), indicating that lighter bulls entering the test were generally more efficient in feed utilization in the test period and had less backfat at the end of the test than heavier entering bulls. Herd of origin of bull accounted for a substantial amount of the total variation (> 16%) in feed/gain and ultrasonic backfat thickness (p = 0.08), indicating that a prolonged aqjustment period was needed to reduce the influence of herd of origin when assessing aggregate genetic merit of beef bulls for growth rate, feed efficiency and lean meat production using a central station performance testing program.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1073-1090
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• 2018

Since the domestic utility tunnels were built mainly in the development project of the new city, they are all in the form of cut-and-cover box tunnel. But, in the case of overseas construction of utility tunnels for existing urban areas, the bored tunnel types are mainly adopted. It is reasonable to install bored tunnels in a downtown area because it is difficult to block the roads or install bypass roads due to heavy traffic and civil complaints. In order to activate the utility tunnels in bored type, it is necessary to secure optimized cross-sectional design technology considering the optimal supplying capacity and mutual influencing factors (Thermal Interference, electrolytic corrosion, efficiency of the maintenance, etc.) of utilities (power cables, telecommunication cables, water pipes, etc.). The optimal cross-section design method for bored utility tunnels is ultimately to derive the optimal arrangement technique for the utilities. In order to develop the design methods, firstly, the cases of tunnel cross-section (Shield TBM, Conventional Tunneling) in overseas shall be investigated to analyze the characteristics of the installation of utilities in the section and installation of auxiliary facilities, It is necessary to sort out and analyze the criteria related to the inner cross-section design (arrangement) presented in the standards and guidelines.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.663-671
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• 2017

This study analyzed the determinants influencing competitiveness of artificial intelligence industry of Korea. Analysis showed that the factors having the greatest influence on the national competitiveness of the artificial intelligence industry were, in decreasing order of importance, R&D, capital, and ICT competitiveness. Given the capital-intensive characteristic of the artificial intelligence technology, it is important to enhance the national R&D capacity in artificial intelligence technology and ICT, and to make substantial investments in the establishment of related infrastructure. Considering that the development and utilization of ICT infrastructure serves as the basis for artificial intelligence technology, the high standards of Korean consumers are expected to have a positive catalytic effect on the acquisition of national competitiveness for the artificial intelligence industry. For companies to respond in a timely manner to the rapid dissemination and high impact of artificial intelligence technology, they must prepare for such advancements by improving their competencies.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.153-160
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• 2012

Various social problems such as traffic congestion, car accidents and environmental problems(air pollution, noises etc.) have been happening in the Seoul metropolitan area that has the car oriented traffic system providing cars continuously. Along with this, the financial burden caused by current oil price anxiety made paradigm shift from caroriented to public transportation-oriented. Its typical example is an arterial branch bus system changing(bus lane through the center of main road) started in Seoul in July, 2004. But study on safety analysis of bus lane and characteristic of accidents are not sufficient enough to now. The bus lanes are expanded to provide roads for better traffic operation and accidents between buses and pedestrians or ordinary vehicles are considered main problems. This study divided each bus route of median bus lane(bus-only lane through the center of main roads) and bus lane at roadside by intersection and collected and analysed data about influence variables of bus accidents chosen in each section. We constructed a logistic model using collected data. As a result, bus lane at roadside are used by both buses and other kinds of vehicles differently from median bus lane and showed such characteristic in accident influence. Therefore access management to factors causing conflict and improvement of operation management are required. In case of median bus lane, the more buses moving general vehicle lane and traffic volume of section were, the more accidents happened. In case that stop line of center lane is not backward, view blocking of vehicles turning left caused accidents.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.5
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• pp.593-600
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• 2014

In this paper, Radar cross section (RCS) calculations of advanced naval vessels model with RCS reduction methods are simulated and RCS results are discussed. Especially, this paper are mainly focusing on the facts influencing on RCS, the ways minimizing RCS and material characteristics of RCS changing-rate. RCS analysis results are given for a DDG-1000 type advanced naval vessels, which show that as the elevation angle increased 10 degree, the mean RCS value increased 23.91 dBsm. Also, as the superstructure angle increased 6 degree, the mean RCS value reduced 1.27 dBsm. Finally, the radar absorbing material attachment at the front and back superstructure have been reduced 2.27 dBsm in terms of mean RCS value.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.143-154
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• 2013

PURPOSES: Design of approach roads of rest areas in highway has many drawbacks such as geometric design elements. There has been traffic accidents occured in these approach roads of rest areas. Thus, design criteria is required in order to protect accidents from being occurred. In case of Korea, geometric structure design criteria of entry facilities, such as toll-gate, interchange, junction etc was established. However there are no presence in a detailed standards for geometric structure of the rest area which affiliated road facilities. METHODS: In this study, analytic on accidents was carried out in regards to the entry of geometric structure of resting areas by utilizing a sight survey and an investigation research of traffic accidents. The survey was targeting 135 general service areas. Collisions with physical channelization and safety facilities occurred due to speeding, rapid entry, and etc at the entrance nose section. At the entrance connector roads, accidents caused by speeding, negligence, over-operation of handle of drivers were main reason of accidents. Discriminant analysis were conducted about geometric elements to distinguish influencing factors for traffic accidents. the lengths and access angles of the entrance connector roads were regarded as to have the high relation with traffic accidents. RESULTS: After classifying the design section of resting areas' entry as well as derive design elements on each section, a speed measurement by targeting entry of rest areas and car behavior surveys were performed, then each element's minimum standard was derived through the analyses. According to the speeds at the starting/end point of entrance connector road, the range of the junction setting angle of the entrance connector road is defined as $12^{\circ}{\sim}17^{\circ}$ and the connector length model was suggested. CONCLUSIONS: Suggest improvement plans for existing rest areas that can be applied realistically. This should be corresponded to the standards of entry and exit of developed rest areas.

• Steel and Composite Structures
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• v.23 no.4
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• pp.409-420
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• 2017

This paper theoretically studies the cyclic behavior of hybrid connections between steel coupling beams and concrete shear walls with embedded steel columns. Finite element models of connections with long and short embedded steel columns are built in ABAQUS and validated against the test results in the companion paper. Parametric studies are carried out using the validated FE model to determine the key influencing factors on the load-bearing capacity of connections. A close-form solution of the load-bearing capacity of connections is proposed by considering the contributions from the compressive strength of concrete at the interface between the embedded beam and concrete, shear yielding of column web in the tensile region, and shear capacity of column web and concrete in joint zone. The results show that the bond slip between embedded steel members and concrete should be considered which can be simulated by defining contact boundary conditions. It is found that the loadbearing capacity of connections strongly depends on the section height, flange width and web thickness of the embedded column. The accuracy of the proposed calculation method is validated against test results and also verified against FE results (with differences within 10%). It is recommended that embedded steel columns should be placed along the entire height of shear walls to facilitate construction and enhance the ductility. The thickness and section height of embedded columns should be increased to enhance the load-bearing capacity of connections. The stirrups in the joint zone should be strengthened and embedded columns with very small section height should be avoided.