• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.157-171
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• 2009

A 151 storey super high-rise building located in an area of reclaimed land constructed over soft marine clay in Songdo, Korea is currently under design. This paper describes the design process of the foundation system of the supertall tower, which is required to support the large building vertical and lateral loads and to restrain the horizontal displacement due to wind and seismic forces. The behaviour of the foundation system due to these loads and foundation stiffness influence the design of the building super structure, displacement of the tower, as well as the raft foundation design. Therefore, the design takes in account the interactions between soil, foundation and super structure, so as to achieve a safe and efficient building performance. The site lies entirely within an area of reclamation underlain by up to 20m of soft to firm marine silty clay, which overlies residual soil and a profile of weathered rock. The nature of the foundation rock materials are highly complex and are interpreted as possible roof pendant metamorphic rocks, which within about 50m from the surface have been affected by weathering which has reduced their strength. The presence of closely spaced joints, sheared and crushed zones within the rock has resulted in deeper areas of weathering of over 80m present within the building footprint. The foundation design process described includes the initial stages of geotechnical site characterization using the results of investigation boreholes and geotechnical parameter selection, and a series of detailed two- and three-dimensional numerical analysis for the Tower foundation comprising over 172 bored piles of varying length. The effect of the overall foundation stiffness and rotation under wind and seismic load is also discussed since the foundation rotation has a direct impact on the overall displacement of the tower.

• 전력전자학회논문지
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• 제25권5호
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• pp.376-384
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• 2020

An energy storage system is composed of lithium-ion batteries in modern applications. Batteries are regarded as storage devices for renewable and residual energy. The failure of batteries can cause the performance reduction and explosion of battery systems. High maintenance cost is essential when dealing with the problem of battery safety. Therefore an accurate health diagnosis is required to ensure the high reliability of battery systems. A battery pack is a combination of single cells in series and parallel connections. A battery pack has to consider various factors to assess battery health. Battery health involves conventional factors and additional factors, such as cell-to-cell imbalance. For large applications, state-of-health (SOH) can be inaccurate because of the lack of factors that indicate the state of the battery pack. In this study, six characterization factors are proposed for improving the SOH estimation of battery packs. The six proposed characterization factors can be regarded as health indicators (HIs). The six HIs are applied to the principal component analysis (PCA) algorithm. To reflect information regarding capacity, voltage, and temperature, the PCA algorithm extracts new degradation factors by using the six HIs. The new degradation factors are applied to a multiple regression model. Results show the advancement and improvement of SOH estimation.

• Structural Engineering and Mechanics
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• 제44권4호
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• pp.431-448
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• 2012

In this paper, the first-order shear deformation theory (FSDT) (Mindlin) for continuum incorporating surface energy is exploited to study the static behavior of ultra-thin functionally graded (FG) plates. The size-dependent mechanical response is very important while the plate thickness reduces to micro/nano scales. Bulk stresses on the surfaces are required to satisfy the surface balance conditions involving surface stresses. Unlike the classical continuum plate models, the bulk transverse normal stress is preserved here. By incorporating the surface energies into the principle of minimum potential energy, a series of continuum governing differential equations which include intrinsic length scales are derived. The modifications over the classical continuum stiffness are also obtained. To illustrate the application of the theory, simply supported micro/nano scaled rectangular films subjected to a transverse mechanical load are investigated. Numerical examples are presented to present the effects of surface energies on the behavior of functionally graded (FG) film, whose effective elastic moduli of its bulk material are represented by the simple power law. The proposed model is then used for a comparison between the continuum analysis of FG ultra-thin plates with and without incorporating surface effects. Also, the transverse shear strain effect is studied by a comparison between the FG plate behavior based on Kirchhoff and Mindlin assumptions. In our analysis the residual surface tension under unstrained conditions and the surface Lame constants are expected to be the same for the upper and lower surfaces of the FG plate. The proposed model is verified by previous work.

• Earthquakes and Structures
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• 제8권3호
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• pp.619-637
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• 2015

A field based non-destructive hardness method is being developed to determine plastic strain in steel elements subjected to seismic loading. The focus of this study is on the active links of eccentrically braced frames (EBFs). The 2010/2011 Christchurch earthquake series, especially the very intense February 22 shaking, which was the first earthquake worldwide to push complete EBF systems into their inelastic state, generating a moderate to high level of plastic strain in EBF active links for a range of buildings from 3 to 23 storeys in height. Plastic deformation was confined to the active links. This raised two important questions: what was the extent of plastic deformation and what effect does that have on post-earthquake steel properties? A non-destructive hardness test method is being used to determine a relationship between hardness and plastic strain in active link beams. Active links from the earthquake affected, 23-storey Pacific Tower building in Christchurch are being analysed in the field and laboratory. Test results to date show clear evidence that this method is able to give a good relationship between plastic strain and demand. This paper presents significant findings from this project to investigate the relationship between hardness and plastic strain that warrant publication prior to the completion of the project. Principal of these is the discovery that hot rolled steel beams carry manufacturing induced plastic strains, in regions of the webs, of up to 5%.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권6호
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• pp.8-17
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• 2013

The contamination of chlorinated ethenes at an industrial complex, Wonju, Korea, was examined based on sixteen rounds of groundwater quality data collected from 2009 to 2013. Remediation technologies such as soil vapor extraction, soil flushing, biostimulation, and pumping-and-treatment have been applied to eliminate the contaminant sources of trichloroethylene (TCE) and to prevent the migration of TCE plume from remediation target zones. At each remediation target zone, temporal monitoring data before and after the application of remediation techniques showed that the aqueous concentrations of TCE plume present at and around the main source areas decreased significantly as a result of remediation technologies. However, the TCE concentration of the plumes at the downstream area remained unchanged in response to the remediation action, but it showed a great fluctuation according to seasonal recharge variation during the monitoring period. Therefore, variations in the contaminant flux across three transects were analyzed. Prior to the remediation action, the concentration and mass discharges of TCE at the transects were affected by seasonal recharge variation and residual DNAPLs sources. After the remediation, the effect of remediation took place clearly at the transects. By tracing a time-series of plume evolution, a greater variation in the TCE concentrations was detected at the plumes near the source zones compared to the relatively stable plumes in the downstream. The difference in the temporal profiles of TCE concentrations between the plumes in the source zone and those in the downstream could have resulted from remedial actions taken at the source zones. This study demonstrates that long term monitoring data are useful in assessing the effectiveness of remediation practices.

• Archives of Plastic Surgery
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• 제48권5호
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• pp.528-533
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• 2021

Bladder acontractility affects several thousand patients in the United States, but the available therapies are limited. Latissimus dorsi detrusor myoplasty (LDDM) is a therapeutic option that allows patients with bladder acontractility to void voluntarily. Our goal was to conduct a systematic review of the literature to determine whether LDDM is a better option than clean intermittent catheterization (CIC) (standard treatment) in patients with bladder acontractility. On January 17, 2020, we conducted a systematic review of the PubMed/MEDLINE, Cochrane Clinical Answers, Cochrane Central Register of Controlled Trials, Embase, and ClinicalTrials.gov databases, without time frame limitations, to identify articles on the use of LDDM for bladder acontractility. Of 75 potential articles, 4 fulfilled the eligibility criteria. The use of LDDM to treat patients with bladder acontractility was reported in four case series by the same group in Europe. Fifty-eight patients were included, and no comparison groups were included. The most common cause of bladder acontractility was spinal cord injury (n=36). The mean (±standard deviation) operative time was 536 (±22) minutes, postoperative length of hospital stay ranged from 10 to 13 days, and follow-up ranged from 9 to 68 months. Most patients had complete response, were able to void voluntarily, and had post-void residual volume less than 100 mL. Although promising outcomes have been obtained, evidence is still weak regarding whether LDDM is better than CIC to avoid impairment of the urinary tract among patients with bladder acontractility. Further prospective studies with control groups are necessary.

• Journal of Korean Dental Science
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• 제12권1호
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• pp.5-12
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• 2019

Purpose: To determine the benefits of autogenous tooth bone (ATB) graft in combination with platelet-rich plasma (PRP) in the rates of success and survival of dental implants placed simultaneously with maxillary sinus floor augmentation (MSFA). Materials and Methods: Patients who visited the Department of Oral and Maxillofacial Surgery at Ulsan University Hospital from 2012 to 2014 and underwent simultaneous placement of implants with MSFA using ATB plus PRP were included in the study. Success and survival rates of the implants were evaluated based on the parameters of age and sex of the patient, site, follow-up period, residual bone height before surgery, diameter, and length of implant, sinus mucosa impairment, and postoperative complications. Result: A total of 23 patients and 67 implants were included in this study. The average age of the patients was $53.78{\pm}10.00$ years. The average follow-up period after installation of the prosthesis was $53{\pm}5$ months. The success and survival rates of the implants after placement of prosthesis were 95.52% and 97.01%, respectively. Conclusion: Combination of ATB and PRP showed high overall success rate, and it can be concluded that this combination is a predictable bone graft procedure for MSFA.

• Steel and Composite Structures
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• 제31권6호
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• pp.575-589
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• 2019

The main focus of this study is to numerically investigate the influence of strong earthquake and tsunami-induced wave impact on the response and behavior of a cable-stayed steel bridge with large caisson foundations, by assuming that the earthquake and the tsunami come from the same fault motion. For this purpose, a series of numerical simulations were carried out. First of all, the tsunami-induced flow speed, direction and tsunami height were determined by conducting a two-dimensional (2D) tsunami propagation analysis in a large area, and then these parameters obtained from tsunami propagation analysis were employed in a detailed three-dimensional (3D) fluid analysis to obtain tsunami-induced wave impact force. Furthermore, a fiber model, which is commonly used in the seismic analysis of steel bridge structures, was adopted considering material and geometric nonlinearity. The residual stresses induced by the earthquake were applied into the numerical model during the following finite element analysis as the initial stress state, in which the acquired tsunami forces were input to a whole bridge system. Based on the analytical results, it can be seen that the foundation sliding was not observed although the caisson foundation came floating slightly, and the damage arising during the earthquake did not expand when the tsunami-induced wave impact is applied to the steel bridge. It is concluded that the influence of tsunami-induced wave force is relatively small for such steel bridge with large caisson foundations. Besides, a numerical procedure is proposed for quantitatively estimating the accumulative damage induced by the earthquake and the tsunami in the whole bridge system with large caisson foundations.

• 한국해양공학회지
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• 제32권6호
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• pp.492-501
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• 2018

The following results were obtained from a series of studies to accumulate data to reduce the coefficient of friction for press dies by performing tribological tests before and after the UNSM treatment of SM45C. The UNSM-treated material had a nano-size surface texture, high surface hardness, and large and deep compressive residual stress formation. Even when the load was doubled, the small amount of abrasion, small weight of the abrasion, and width and depth of the abrasion did not increase as much as those for untreated materials. When loads of 5 N, 7.5 N, and 10 N were applied to the untreated material of SM45C, the coefficient of friction was approximately 0.76-0.78. With the large specimen, a value of 0.72-0.78 was maintained at a load of 50 N despite the differences in the size of the wear specimen and working load. Tribological tests of large specimens of SM45C treated with UNSM under tribological conditions of 100 N and 50 N showed that the frictional coefficient and time constant stably converged between 0.7 and 0.8. The friction coefficients of the small specimens treated with UNSM showed values between 0.78 and 0.75 under 5 N, 7.5 N, and 10 N. The friction coefficients of the SM45C treated with UNSM were comparable to each other.

• 아태비즈니스연구
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• 제11권4호
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• pp.65-81
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• 2020

Purpose - This research aims to investigate how consumers' eco-friendly product choice ratio changes as the benefits of eco-friendly products are framed as (1) non-monetary benefits, (2) monetary gain integrated with the loss or (3) monetary gain segregated from the loss. Design/methodology/approach - A mixed-design, scenario-based choice experiment was conducted. A series of chi-square tests and residual analyses were conducted to analyze the data. Findings - When the monetary gain was larger or slightly smaller than the loss, the participants' eco-friendly product choice ratio was higher when the monetary gain was integrated with the loss than those in the other two conditions. When the monetary gain was significantly smaller than the loss, the participants' eco-friendly product choice ratio was lower when the monetary gain was integrated with the loss than those in the other conditions. The ratio did not differ between the latter two conditions. Research implications or Originality - This research shows that marketers should frame the benefits of eco-friendly products and their costs in different manners depending on the relative magnitudes of them. This research also complements the existing literature by comparing the effectiveness of non-monetary framing of eco-friendly product benefits with that of monetary framing following hedonic editing hypothesis.