• Steel and Composite Structures
• /
• v.17 no.3
• /
• pp.237-252
• /
• 2014

The use of composite structures is increasingly present in civil building works. Composite Box Girder Bridges (CBGB), particularly, are study of effect of shear connector's numbers and distribution on the behavior of CBGBs is submitted. A Predicti structures consisting of two materials, both connected by metal devices known as shear connectors. The main functions of these connectors are to allow for the joint behavior of the girder-deck, to restrict longitudinal slipping and uplifting at the element's interface and to take shear forces. This paper presents 3D numerical models of CBGBs to simulate their actual structural behavior, with emphasis on the girder-deck interface. Additionally, a Prediction of several FE models is assessed against the results acquired from a field test. A number of factors are considered, and confirmed through experiments, especially full shear connections, which are obviously essential in composite box girder. A good representation for shear connectors by suitable element type is considered. Numerical predictions of vertical displacements at critical sections fit fairly well with those evaluated experimentally. The agreement between the FE models and the experimental models show that the FE model can aid engineers in design practices of box girder bridges. Preliminary results indicate that number of shear studs can be significantly reduced to facilitate adoption of a new arrangement in modeling CBGBs with full composition. However, a further feasibility study to investigate the practical and economic aspects of such a remedy is recommended, and it may represent partial composition in such modeling.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.3
• /
• pp.1404-1415
• /
• 2016

Because of the properties of software such as invisibility, complexity, and changeability, software configuration management (SCM) for software artifacts generated during software life-cycle has been used for guarantee of the quality of the software. However, the existing SCM system has only focused on code artifacts and software development document artifacts such as Software Requirements Specification (SRS), Software Design Description (SDD), and Software Test Description (STD). Moreover, software research-oriented project comes out late the code artifacts and the software development document artifacts. Therefore, there is a need for trace and management of software research document artifacts composed of highly abstracted non-functional requirements like 'the purpose of the project', 'the objectives', and 'the progress' before generation of the code artifacts and the software development document artifacts for a long time. Nevertheless, the existing SCM system cannot trace and manage them. In this paper, we propose content-based configuration management system comprised of the relevance link generation phase and content-based testing phase to trace and manage them. The preliminary application results show applicability and feasibility of the proposed system.

• Journal of Powder Materials
• /
• v.25 no.4
• /
• pp.327-330
• /
• 2018

This study is conducted as a preliminary research to verify the feasibility of Ti-based Oxide dispersion strengthened (ODS) alloy. Pure-Ti powder is mixed with $Y_2O_3$ powder and subsequently, mechanically alloyed at $-150^{\circ}C$. The Ti-based ODS powder is hot-isostatically pressed and subsequently hot-rolled for recrystallization. The microstructure consists of elongated grains and Y excess fine particles. The oxide particle size is larger than that of the typical Fe-based ODS steel. Tensile test shows that the tensile ductility is approximately 25%, while the strength is significantly higher than that of pure Ti. The high-temperature hardness of the Ti-ODS alloy is also significantly higher than that of pure Ti at all temperatures, while being lower than that of Ti-6Al-4V. The dimple structure is well developed, and no evidence of cleavage fracture surface is observed in the fracture surface of the tensile specimen.

• ETRI Journal
• /
• v.31 no.6
• /
• pp.688-694
• /
• 2009

In this paper, we present the results of a preliminary study on the piezoelectric energy harvesting performance of a Zr-doped $PbMg_{1/3}Nb_{2/3}O_3-PbTiO_3$ (PMN-PZT) single crystal beam. A novel piezoelectric beam cantilever structure is used to demonstrate the feasibility of generating AC voltage during a state of vibration. The energy-harvesting capability of a PMN-PZT beam is calculated and tested. The frequency response of the cantilever device shows that the first mode resonance frequency of the excitation model exists in the neighborhood of several hundreds of hertz, which is similar to the calculated value. These tests show that several significantly open AC voltages and sub-mW power are achieved. To test the possibility of a small scale power source for a ubiquitous sensor network service, energy conversion and the testing of storage experiment are also carried out.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.18 no.6
• /
• pp.227-237
• /
• 2015

From January 2013 to October 2015, weed invasion control techniques was tested in the test road of Jungbunaeryuk expressway so as to collect preliminary data for the management methods of the upper exterior banking of expressway shoulders. Then, monitoring was conducted and its results are as follows. Mat (sheet), solidifying agent, and mulching (wood chips) were applied for the test and their initial effects of preventing weed invasion were all excellent. It was found that the homogeneity of the wood chip mulching method needs to improve. In the mat method and the mulching method were found to have the most excellent economic feasibility and aesthetics, respectively. The covering degree was found to be the highest at 80% in the control site, followed by the wood chip site at 20% and the solidifying agent site and the non-woven fabric site at 5% each. As for species diversity, the control had the largest variety of species. Two years after the construction, many different species of plants invaded and were growing. Plants including weed didn't tend to invade the slopes applied with non-woven fabric. In addition, weed didn't invade the solidifying agent site and the aesthetics of the upper exterior banking of expressway shoulders was found to be excellent. The wood chip site was found to require consistent management for preventing weed invasion. The mat (sheet) site, the solidifying agent site, and the wood chip mulching site were found to have excellent weed prevention effects. As time passed, the mat (sheet) site and the solidifying agent site showed better weed prevention effects. However, they need consistent monitoring for further application.

• Geomechanics and Engineering
• /
• v.12 no.4
• /
• pp.611-626
• /
• 2017

The research reported herein is concerned with the model testing of piles socketed in soft rock which was simulated by cement, plaster, sand, water and concrete hardening accelerator. Model tests on a single pile socketed in simulated soft rock under axial cyclic loading were conducted and the bearing capacity and accumulated deformation characteristics under different static, and cyclic loads were studied by using a device which combined oneself-designed test apparatus with a dynamic triaxial system. The accumulated deformation of the pile head, and the axial force, were measured by LVDT and strain gauges, respectively. Test results show that the static load ratio (SLR), cyclic load ratio (CLR), and the number of cycles affect the accumulated deformation, cyclic secant modulus of pile head, and ultimate bearing capacity. The accumulated deformation increases with increasing numbers of cycles, however, its rate of growth decreases and is asymptotic to zero. The cyclic secant modulus of pile head increases and then decreases with the growth in the number of cycles, and finally remains stable after 50 cycles. The ultimate bearing capacity of the pile is increased by about 30% because of the cyclic loading thereon, and the axial force is changed due to the applied cyclic shear stress. According to the test results, the development of accumulated settlement is analysed. Finally, an empirical formula for accumulated settlement, considering the effects of the number of cycles, the static load ratio, the cyclic load ratio and the uniaxial compressive strength, is proposed which can be used for feasibility studies or preliminary design of pile foundations on soft rock subjected to cyclic loading.

• The korean journal of orthodontics
• /
• v.52 no.2
• /
• pp.123-130
• /
• 2022

Objective: To evaluate if a remote digital monitoring system added at the end of orthodontic treatment could positively influence the retention phase by reducing the occurrence of misfit of removable appliances, number of emergency appointments (EA), and orthodontic relapse. Methods: Twenty-seven patients who completed active orthodontic treatment were divided into the study and control groups. In addition to the standard chairside follow-up appointments at month 1 (T1), month 3 (T2), month 6 (T3), the study group patients were monitored using Dental Monitoring^® with monthly intra-oral scans. Occurrence of misfit of removable retainers, number of EAs, and intercanine width change were recorded for both groups. Differences in EAs and retainer fit were assessed using the chi-square test. Intra-group and inter-group differences in the intercanine width were assessed with Friedman test and Mann-Whitney U test, respectively (α = 0.05). Results: The study group showed a significantly lower occurrence of misfit of removable retainers (p = 0.027) compared to the control group. No significant inter- and intra-group difference was found in the EAs and intercanine width change at each time-point. Conclusions: Integrating remote monitoring systems, such as Dental Monitoring^®, to the retention phase of the orthodontic treatment may lower the occurrence of misfit of removable retainers. However, a small sample size and a short observation period limit the strength of this evidence. These preliminary results tentatively suggest that remote monitoring technologies may be beneficial, especially during the COVID-19 pandemic, when the regularity of in-office visits might be disrupted.

• Journal of the Korean Geotechnical Society
• /
• v.29 no.8
• /
• pp.37-51
• /
• 2013

An energy pile encases heat exchange pipes to exchange thermal energy with the surrounding ground formation by circulating working fluid through the pipes. An energy pile has many advantages in terms of economic feasibility and constructability over conventional Ground Heat Exchangers (GHEXs). In this paper, a coil-type PHC energy pile was constructed in a test bed and its thermal performance was experimentally and numerically evaluated to make a preliminary design. An in-situ thermal response test (TRT) was performed on the coil-type PHC energy pile and its results were compared with the solid cylinder source model presented by Man et al. (2010). In addition, a CFD numerical analysis using FLUNET was carried out to back-analyze the thermal conductivity of the ground formation from the Ttype PHC energy RT result. To study effects of a coil pitch of the coil-type heat exchange pipe, a thermal interference between the heat exchange pipes in PHC energy piles was parametrically studied by performing the CFD numerical analysis, then the effect of the coil pitch on thermal performance and efficiency of heat exchange were evaluated. Finally, an equivalent heat exchange efficiency factor for the coil-type PHC energy pile in comparison with a common multiple U-type PHC energy pile was obtained to facilitate a preliminary design method for the coil-type PHC energy pile by adopting the PILESIM2 program.

• The Korean Journal of Rehabilitation Nursing
• /
• v.6 no.1
• /
• pp.79-89
• /
• 2003

Purpose: This research with one group pre-post design was carried out to test the practical feasibility to administrate the Music Movement program developed for the stroke patients. Subjects: 12 stroke survivors at "J" Public Health Center in Seoul. were participated in. The average age was 68 years old, the ratio of sex was almost 5.8:4.2, the duration of was almost over 1 year. Method: Music Movement program was conducted for 2 hours ${\times}$ 1day ${\times}$ 6 weeks. The contents of Music Movement program were consisted of the preparatory activities, main activities and the wrap up activities. The preparatory activities are ice braking, greeting, explanation of the aims of music movement program, and introduction of stroke disease and ROM exercise. The main activities are the body motions with singing and playing musical instruments. The wrap up activities are stretching and joints and discussion of home activities. Data Collection: The outcome variables are muscle strength, finger pinch power, ROMs, flexibility, depression, and life satisfaction. Depression was measured by CES-D(Kim, I. J., 1999), life satisfaction by ladder scale(McDowell & Newell, 1996), and ADL state(Holbrook & Skilbeck, 1983). Data Analysis: SPSS/PC 10.0 for Window was used. Wilcoxon Signed Ranks Test was used to analyze outcome measures. The level of statistical significance was set at p<.05. Results: This program was effective to decrease the depression level of subjects(p<.05). The muscle strength, hand grip power, ROMs, life satisfaction, and rehabilitation state of the subjects were slightly increased but no significant differences were found between the pre and post test. Additionally every patient replied that they were very satisfied and expressed their appreciation for this program very much. Of course they strongly want to continue to participate in and meet the peer group again. Conclusion: Considering these results, the practical feasibility of Music Movement program can be supported. Therefore, this Music Movement program can be examined with the quasi-experimental design with control group and ongoing reviews. After that, this program would be applied in public health centers, medical institutes, and welfare centers for the rehabilitation of stroke patients.

• Journal of Korean Society of Environmental Engineers
• /
• v.36 no.2
• /
• pp.84-95
• /
• 2014

Recently, as a variety of techniques of CMF (Compressed media filter) that has advantages of high porosity and compressibility have been developed in the U.S. and Japan. Therefore, the interest of intensive wastewater treatment using CMF has grown. This study examined the feasibility of CMF with varying sewage water quality to determine the optimum operating conditions. A preliminary tracer test that investigated the filtering process under various compression and flow rate conditions was performed. In a high compression condition, different porosities were applied to each depth of the column. Therefore, a distinct difference between a theoretical value and results of tracer test was observed. For the TSS (Total suspended solid) removal and particle size distribution of CMF for pre-treatment water under the various compression conditions, the compression ratio of 30 percent as the optimal condition showed greater than 70% removal efficiency. In addition, the compression ratio of >15% was required to remove small-sized particles. Also, an additional process such as coagulation is necessary to increase the removal efficiency for < $10{\mu}m$ particles, since these small particles significantly influence the effluent concentration. Modeling results showed that as the compression rate was increased, TSS removal efficiency in accordance with each particle size in the initial filtration was noticeably observed. The modeling results according to the depth of column targeting $10{\mu}m$ particles having the largest percentage in particle size distribution showed that 150-300 mm in filter media layer was the most active with respect to the filtering.