• Journal of the Korea Concrete Institute
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• 제18권5호
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• pp.603-610
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• 2006

The external unbonded strengthening offers advantages in speed and simplicity of installation over other strengthening techniques. Unlike externally bonded steel plate or carbon fiber sheet, surface preparation of the concrete for installation of high-tension bar is not required and installation is not affected by environmental conditions. Anchoring pin or anchoring plate are installed at the end of beam to connect the high-tension bar to concrete beam. The deviator are used in order that supplementary external bars would follow the curvature of the tested beam. A set often laboratory tests on reinforced concrete beam strengthened using the technique are reported. The main test parameters are the section area of strengthening bar, the depth of deviator and the number of deviators. The paper provides a general description of structural behavior of beams strengthened using the technique. The test result of strengthened beam are compared with those from a reference specimen. It is shown that the reinforcing technique can provide greater strength enhancements to unstrengthened beam and that the provision of deviator enhances efficiency. The ultimate moment of specimen with two deviators was higher than that of specimens with one deviator. It is also shown that the external bars enhance strength of beams in shear.

• Journal of the Korea Concrete Institute
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• 제26권3호
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• pp.267-275
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• 2014

Recently, the construction of curved bridge has increased, thus researchers perform the analytic studies on PSC curved bridge. However, the grid analysis method that are mostly used in the construction industry is not adequate to acquire the precise behavior evaluation of curved PSC briges. Therefore, the precise finite element analysis considering the effective variables were performed to establish the basis for the design method of curved PSC bridge by using 3D elements and bar element. The evaluated variables in this analysis were the number of girders, loading point, section figure, change of prestressing force. The results show the load carrying capacity of the 3 girder type bridge is 200% of that of the 2 girder type, and that applying load on outer girder makes the load resistance capacity and the deflection deviation of 2 girders smaller. The structural capacity of the bridge is improved when the section size is increased, but the efficiency of it is not sufficient enough compare to that of the change of prestressing forces. The change of prestressing forces shows that the camber and the load carrying capacity are linearly increased as PS force is increased. Moreover, when the PS force applied on outer girder is increased than that of inner girder, the deviation of deflection the girders decreases, thereby the stability of the bridge is enhanced.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.309-312
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• 2008

Reinforced concrete (RC) structures have been most widely used because of the economic efficiency. However, it is very weak to tensile stresses and difficult to control deflection due to the heavy self-weight of concrete. Although it is generally known that prestressed concrete structures can be the most effective to overcome the demerit of RC structures, its application is very seldom in domestic construction for the difficult onsite circumstances. The post-tension method, which is well fit for buildings that are mostly indeterminate structures and beneficial for monolithic construction, has been introduced to just a few building construction. The application of full PT method into entire spans makes construction engineers feel very difficult due to the lack of current condition in construction fields. Therefore, this study proposed the partially applied PT method as an alternative, which can improve the deflection control of RC structures and reduce the construction difficulty by applying the PT method in a part of span length as needed, and analyzed its characteristics of structural behavior. In this study, the top anchorage was applied to improve the applicability of partial PT method, and the analysis results of slab behavior were compared to the measured values obtained from the post-tensioned slab constructed by the partial PT method.

• Journal of the Korean Ceramic Society
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• 제39권2호
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• pp.126-134
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• 2002

Fabrication of mortar containing fly ash for high strength structural material was investigated by using a Mechanochemically Processed Cement (MPC) and/or Fly Ash (MPFA), which was compared to the specimen (at the same fabrication condition of fly ash adding contents (10, 20 and 30 wt%) and curing time (7 and 28 days)) fabricated by using Ball-mill Processed Cement (BPC) and As Received Fly Ash (ARFA) in terms with compressive strength and microstructures. Mortar specimen fabricated by using MPC and ARFA showed 5-11% higher compressive strength than that in the case of using BPC and ARFA, and mortar specimen by using BPC and MPFA represented 10-20% higher compressive strength than that for the case of using BPC and ARFA. Furthermore, mortar specimen fabricated by simultaneously using MPC and MPFA exhibited about 24% higher value of compressive strength than that for the case of using BPC and ARFA, which was considered to be synergic efficiency in increasing compressive strength. Increased compressive strength as above mentioned is considered to be caused by mutually increased affinity between cement and fly ash induced during mechanochemical Processing(MP).

• Journal of the Korea Convergence Society
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• 제11권7호
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• pp.113-123
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• 2020

The purpose of this study is to quantitatively demonstrate that rational and emotional factors in urban tourist facilities affect visitor satisfaction, positive word of mouth and subsequent revisits. Therefore, the researcher used structural modeling methodology to test the paths and relationships between the rational and emotional perception, satisfaction, word of mouth, and exogenous variables (aesthetics, economic utility, accessibility, emotional attachment, etc.) of urban tourism facilities perceived by users. As a result of the study, users of urban tourism facilities are affected by customer satisfaction such as ease, usability, and pleasure based on intangible assets such as kindness, aesthetics, symbolism, attachment, and rational factors, which are emotional impressions of urban tourism facilities, and utility, and customer satisfaction. These were found to have a positive and lasting effect on users' perceptions of the facility. Therefore, if the rational and emotional values of urban tourism facilities are considered and integrated in marketing, efficiency can be maximized in terms of satisfaction, word of mouth, and future revisits. The researcher considered that this study could contribute to the revitalization of the tourism industry and the city as a whole through the improvement and utilization of various tourism facilities possessed by the city.

• Journal of the Korean Recycled Construction Resources Institute
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• 제5권3호
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• pp.84-93
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• 2010

Compaction of backfill material of Underground power lines is difficult, especially under pipeline. so it could cause structural problem because of low compaction efficiency. So various methods have been taken to solve the problem and one of them is CLSM(Controled low-strength material accelerated flow ability). But In other countries, these are already in progress for a long time to research and development and recently on practical steps. But, in our country, study for only general structures, not for underground power line structure that is being constructed at night rapidly. In this study, we performed property tests and indoor & outdoor test (3 cases). The tests showed flow ability reached at the limit construction(160 mm) flowability by 9 to 15 minute after starting to mix, and construction buoyant is lowering after placing CLSM by 70 % of theoretical buoyant that is calculated by unit weight of material. In this paper, we performed indoor tests and outdoor tests to estimate mechanical properties and to suggest construction method(using batch plant, setting spacer at 1.8 m and placing at 2m) for CLSM that using surplus soil. And the test showed good results for construction quality, workability and structure safety.

• Asia pacific journal of information systems
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• 제19권3호
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• pp.151-179
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• 2009

The purpose of this study is to make an empirical analysis on the factors affecting the intention for the continuous use of the BSC system, which has been recently spread in the public sector. Because the object of acceptance is the performance management system based on BSC (Balanced Scorecard) implemented in the form of information systems, this study proposes a research model by applying TAM (Technology Acceptance Model). Independent variables are factors affecting the acceptance of BSC system such as training, communication, IS support, CEO support and personal innovativeness, and we examine their effects on the dependent variable, namely, intention on continuous use via mediating variables: perceived usefulness and perceived ease of use. A questionnaire survey was conducted with public institutions(firms) that had introduced and were operating the BSC system; 264 valid questionnaires are adopted. Collected data are analyzed using SPSS 16.0 and AMOS 7.0. Results of reliability test show that all analyzed data are reliable. In validity test, one item regarding communication was excluded; 9 latent variables and 34 observed variables are used in the final analysis. Based on the results of the hypothesis test through path analysis using a structural equation model, 10 out of 16 hypotheses are accepted. Factors affecting perceived usefulness are training and IS(Information System) support. The analysis results indicate that perceived ease of use is mainly affected by IS support, CEO support, and personal innovativeness among the factors related to the acceptance of the BSC system. This suggests that, contrary to the expectation that the BSC system may be used without difficulty, the management's active support is required in order to attain expected improvement in productivity and work efficiency. This was also pointed out in case studies on the construction of the BSC system in public sectors. On the other hand, perceived ease of use is found to affect perceived usefulness. This supports the results of previous researches on TAM. Perceived ease of use and perceived usefulness are found to affect the attitude towards the use of the system. The intention on continuous use is affected more by perceived usefulness than by the attitude towards the use of system. This result supports the results of previous researches on TAM, showing that the BSC system is utilized substantially in worksites. This study is considered meaningful in that it was actually performed on users at public institutions(firms) that had introduced the BSC system and that it empirically tested hypotheses on the acceptance of the BSC system by applying TAM to the research model.

• Journal of the Korean Society of Marine Environment & Safety
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• 제24권6호
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• pp.818-824
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• 2018

CFRP is often used as lightweight hull material for luxury yachts or special-service ships. An electric propulsion system is also eco-friendly, and has been trialled to equip a small vessel as its main propulsion. In this study, replacing the hull materials and propulsion system with CFRP and electric motors, we made an estimate of the effect of weight reduction and compared it to the original design, for this purpose a case study was conducted on a 45-ft yacht. When redesigning structures with CFRP, we applied the reinforcement content of the carbon fiber in the same way as the original (GC = 0.4), and when changing to the electric propulsion system, we designed motors and battery packs to achieve the same performance as the original. The result showed that CFRP and the electric propulsion system could make the structural and machinery weights 45 % and 58 % lighter, respectively. However, in terms of efficiency, it was confirmed that the electric propulsion system is practically inefficient because it requires a huge amount of battery packs for the same navigation range with diesel engines.

• Journal of Korean Society of Steel Construction
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• 제18권6호
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• pp.793-804
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• 2006

Various PSC and steel-concrete composite railway bridges are being developed for short-medium spans with structural and economic efficiency. According to the design concept, the prestressed composite girder bridge has the advantages of being lightweight and having low girder depth, with the capacity for long spans. However, the dynamic behavior under a passing train is one of the critical issues concerning these railway bridges designed with more flexibility. Therefore, it is very important to evaluate the modal parameters before performing dynamic analyses. In this paper, real-scale prestressed composite girders were fabricated as a test model and modal testing was carried out to evaluate modal parameters including natural frequency and modal damping ratio. During the modal testing, a digitally controlled vibration exciter as well as an impact hammer was applied to obtain frequency-response functions, and the modal parameters were also evaluated after the fracture of test models. With application of reliable properties from modal tests, the estimation of dynamic performances of prestressed composite girder railway bridges can be obtained from various parametric studies on dynamic behavior under the passage of a moving train.

• Korean Journal of Social Welfare
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• 제57권2호
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• pp.205-230
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• 2005

This study empirically examines if there is a certain linkage between the production regimes and welfare systems; and if linked, how they are linked. It also investigates what the different regimes performed in terms of economic growth and redistribution. As a matter of fact, we have a series of studies that explores structural diversity of production and welfare. However, the existing studies are limited in that they consider only specific facets of the structure, although the structure of welfare capitalism should be studied as a comprehensive whole. This is the gap which this study tries to overcome. The study is composed of two major parts. The first one is the cluster analysis that examines if Esping-Andersen's notion about three different welfare regime and the thesis of diversity of capitalism can be dealt within a single research framework. The second is the ANOVA analysis investigating if variables of production and welfare are to be statistically different in the trichotomy framework. According to the result of the analyses, we can find at least two important evidences about institutional complementaries of production and welfare. First, Esping-Andersen's framework is useful to comprehensively deal with production as well as welfare. Secondly, there are statistically different regimes of production and welfare in the context of political economic and social policy variables. What is the most striking conclusion of the study is that there is no difference among the regimes in terms of the level of economic efficiency; while we can find a huge differences in terms of the level of welfare effectiveness. In conclusion, there is no substantive evidence to argue that welfare is innately antithesis of economic growth.