• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.288-296
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• 2003

Generally, application of steel pipe pile as deep foundation member needs special requirement for the connection method between steel pipe pile and concrete footing. Even though two types of connection method are suggested in the related specification, type B-method is provident. To investigate real structural behavior of type B connection, several load tests are done with carefully designed experimental system. The purpose of this experiment is mainly focused on the understanding of actual behavior which can be predicted by design theory. At this research stage, vertical and lateral loading test are done for three types of specimen to review stress concentration, formation and behavior of imaginary RC column in the footing and effect of non-slip device installed in the steel pipe pile. The load resistance mechanism in these specific connection method is predicted based on both experimental results. The three-dimensional finite element modeling is also done for the purpose of comparison between numerical and experimental result. With all the results gained from experiment the structural behavior of imaginary RC column in the design concept is confirmed. The role of non-slip device is very important and it affects the resistance capacity with help of composite action of concrete and steel pipe pile.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.234-245
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• 2003

Most of the concrete bridge structures are exposed to damage due to the excessive traffic loading and the aging of the structure. The damage of concrete causes the further deterioration of the function in the concrete structure due to corrosion of the reinforced bars and decohesion between the concrete and the reinforced bar. The quick rehabilitation of the damaged concrete structures has become of great importance in the concrete structural system in order to avoid the further deterioration of the structures. Recently fiber sheets are used for strengthening the damaged concrete structures due to its many advantages such as its durability, non-corrosive nature, low weight, ease of application, cost saving, control of crack propagation, strength to thickness ratio, high tensile strength, serviceability and aesthetic. However, the lack of analytical procedures for assessing the nominal moment capacity by the fiber sheet reinforcement leads to difficulties in the effective process of decisions of the factors in the strengthening procedure. In this work, flexural strengthening effects by fiber sheets bonded on bottom face of the member are studied for the reinforced concrete T beam. In addition, auxiliary flexural strengthening effects by U-type fiber sheets bonded on bottom and side faces of the member to prevent delamination of the bottom fiber sheet are theoretically investigated. The analytical solutions are compared with experimental results of several references to verify the proposed approach. It is shown that the good agreements between the predicted results and experimental data are obtained.

• Korean Journal of Social Welfare
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• v.53
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• pp.311-336
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• 2003

This paper purports to explain the conflicts and compromises between supra-national authority and national welfare state in an era of globalization. For this purpose this paper, first of all, examines if Community law(EU) is directly applicable to member states(direct applicability), and subsequently, if Community law is superior to national law(supremacy). It duly claims that Community law is de facto applicable to member states and thus is superior to national law, but de jure the direct applicability and supremacy of Community law are still ambiguous in practice. Secondly, it briefly describes the development of EU social policy from 'The Rome Treaty(1957)' to 'The Amsterdam Treaty(1997)', and ascertains clear limitations of social dimension of EU. Thirdly, it explains why CEU(Commission of European Union) sequently fails to achieve uniform harmonization policy in the making of social Europe. This paper concludes that 'downward harmonization thesis' or 'convergence thesis' which commonly stresses that globalization seriously impinges on nation-state's policy autonomy and policy capacity is not evidenced at least in the case of EU social policy.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.673-681
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• 2003

This paper describes the experiment that determines the ultimate strength of new uniplanar T-joints made of cold-formed square hollow sections. The new T-joint focused on the configuration of a branch member that is oriented 45 degrees to the plane of the truss and welded to the chord member whose web is stiffened with plate. The strength and failure mode are examined using the existing strength formula for the branch-rotated T-joint $(16.7{\leq}2{\gamma}(B/T){\leq}33.3$ and $0.63{\leq}{\beta}(b1/B){\leq}0.7)$. The test result shows that the capacity of the stiffened joint increases with thicker stiffening plate. The failure mode of the specimen $(2{\gamma}=33.3)$ is stiffened with plate changes from M2 (flange failure) to M3 (combined failure). On the other hand, the failure mode of the specimen $(2{\gamma}=16.7)$ is stiffened with plate changes from M1 ( web failure) to M2 (flange failure)

• Convergence Security Journal
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• v.20 no.4
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• pp.227-236
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• 2020

Peacekeeping operations (PKO), which were based mainly on military operations in the Cold War era, have become diverse in the post-Cold War era. The history of the PKO of Korean police began in 1994 as two policemen were deployed to Somalia for rebuilding law and order in this country, but the role of Korean police in PKO has been limited so far, compared to that of Korean military. At this point when global conflicts escalate does the UN urge its 193 member states to conduct diverse PKO. In particular, maintaining law and order as the primary duty of police is required strictly for law enforcement while the warring country is being rebuilt. In this regard, some member states such as US, China, and Germany have deployed police force in order to play its role in a direct or indirect manner. On the contrary, the extent of the contribution of Korean police in PKO is too insignificant to measure. To this end, here in the present study were analyzed first the trend of global conflicts and the circumstance of law and order in the conflict regions. Then the PKO of police from countries including Republic of Korea, US, China, and Germany were compared, and so was the chronological change of PKO. Last, a measure to expand the capacity of Korean police and for its active role in PKO was proposed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.543-550
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• 2009

This study was performed to prove the possibility of utilizing short plastic fibers made for recycled polyethylene terephthalate (RPET) as a structural material. In order to verify the capacity of RPET fiber, it was compared with polypropylene (PP) fiber, most widely used short synthetic fiber, for fiber volume fraction of 0%, 0.5%, 0.75%, and 1.0%. To measure material properties such as compressive strength, split tensile strength, appropriate tests were performed. Also, to measure the strength and ductility capacities of reinforced concrete (RC) member casted with RPET fiber added concrete, flexural test was performed on RC beams. The results showed that compressive strength decreased, as fiber volume fraction increased. These trends are similarly observed in the tests of PP fiber added concrete specimens. Split cylinder tensile strength of RPET fiber reinforced concrete increased slightly as fiber volume fraction increased. For structural member performance, ultimate strength, relative ductility and energy absorption of RPET added RC beam are significantly larger than OPC specimen. Also, the results showed that ultimate flexural strength and ductility both increased, as fiber volume fraction increased. These trends are similarly observed in the tests of PP fiber added concrete specimens. The study results indicate that RPET fiber can be used as an effective additional reinforcing material in concrete members.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.4 s.50
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• pp.85-94
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• 2006

In the design of bridge piers in seismic area, the ductility requirement is the most important factor. In order to enhance the seismic performance of RC columns, it is necessary to make the ductility of columns larger by covering RC columns with steel tubes or confining RC columns by arranging transverse reinforcements such as hoop ties closely. Using core steel composite columns is useful as one of the reinforcing RC columns. In this paper, quasi-static tests on concrete encased composite columns with single core steel or multiple steel elements were performed to investigate the seismic performance of the composite columns. Eight concrete-encased composite specimens were fabricated. The cross-sections of these specimens are composed of concrete-encased H-shaped structural steel columns and a concrete-encased circular tube with partial in-filled concrete. Test parameters were the amount of the transverse reinforcements, type and number of encased steel member. Through the tests, it was evaluated the ductility of SRC composite specimens. It has become clear from the test results that encased steel elements makes the deformation capacity of the columns to be larger. The displacement ductility and lateral strength of specimen with concrete-encased circular tube were indicated the biggest value.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.1
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• pp.101-113
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• 2015

This paper introduces a numerical analysis method for reinforced-concrete(RC) members exposed to fire and proposes considerations in designing RC structures on the basis of the comparison between numerical results and design codes. The proposed analysis method consists of two procedures of the transient heat transfer analysis and the non-linear structural analysis. To exactly evaluate the structural behavior under fire, two material models are considered in this paper. One is "Under-Fire" condition for the material properties at the high temperature and the other one is "After-Cooling" condition for the material properties after cooling down to air temperature. The proposed method is validated through the correlation study between experimental data and numerical results. In advance, the obtained results show that the material properties which are fittable to the corresponding temperature must be taken into account for an accurate prediction of the ultimate resisting capacity of RC members. Finally, comparison of the numerical results with the design code of EN1992-1-2 also shows that the design code needs to be revised to reserve the safety of the fire-damaged structural member.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.265-275
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• 2016

IT industry has rapidly changed with unlimited competition. In this situation, this article is searching for methods to enhance work engagement(WE) which increases workers' and organizations' performance. Servant leadership(SL) involves organizational change, thus one dimension of SL named commitment to the growth of people(CGP) which focuses on people' development would play a decisive role in IT industry, since member's capacity makes a success of this field. Since CGP would influence on perceived organizational support(POS), workers would have positive attitude to work. Furthermore, expectancy has a critical role for CGP which is related to the future. In future oriented viewpoint, if a leader supported members' growth and they had positive expectancy for the future, they would have higher POS, then WE also will be increased. The purpose of this study is to explain the importance of CGV, expectancy and POS, since they enhance WE which is the key factor for success of IT organizations and members in today.

• Journal of the Korea Concrete Institute
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• v.16 no.4 s.82
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• pp.467-476
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• 2004

Because of crack control by steel bars after cracking the material models for reinforced concrete(RC) differ from those for plain concrete(PL). The nonlinear behavior of columns subjected to lateral load was simulated with reasonable accuracy in 3D analysis by applying distinct material models for RC and PL zone subdivided properly on the section. The shear strain is confirmed to develope unstably with ununiform distribution in out-of-plane direction. And this tendency becomes stronger as the thickness of column member increases in out-of-plane direction. If this ununiformity in strain distribution is not taken into consideration the capacity and the deformability of columns in shear dominant failure are overestimated excessively in two dimensional analysis. By introducing equivalent softening model a behavior of columns can be predicted too in two dimensional analysis.