• Advances in concrete construction
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• 제6권6호
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• pp.645-658
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• 2018

Despite being one of the most abundantly used construction materials because of its exceptional properties, concrete is susceptible to deterioration and damage due to various factors particularly corrosion, improper loading, poor workmanship and design discrepancies, and as a result concrete structures require retrofitting and strengthening. In recent times, Fiber Reinforced Polymer (FRP) composites have substituted the conventional techniques of retrofitting and strengthening of damaged concrete. Most of the research studies related to concrete strengthening using FRP have been performed on undamaged test specimens. This contribution presents the results of an experimental study in which concrete specimens were damaged by mechanical loading and elevated temperature in laboratory prior to application of Carbon Fiber Reinforced Polymer (CFRP) sheets for strengthening. The test specimens prepared using concrete of target compressive strength of 28 MPa at 28 days were subjected to compressive and splitting tensile testing up to failure and the intact pieces of the failed specimens were collected for the purpose of repair. In order to induce damage as a result of elevated temperature, the concrete cylinders were subjected to $400^{\circ}C$ and $800^{\circ}C$ temperature for two hours duration. Concrete cylinders damaged under compressive and split tensile loads were re-cast using concrete and rich cement-sand mortar, respectively and then strengthened using CFRP wrap. Concrete cylinders damaged due to elevated temperature were also strengthened using CFRP wrap. Re-cast and strengthened concrete cylinders were tested in compression and splitting tension. The obtained results revealed that re-casting of specimens damaged by mechanical loadings using concrete & mortar, and then strengthened by single layer CFRP wrap exhibited strength even higher than their original values. In case of specimens damaged by elevated temperature, the results indicated that concrete strength is significantly dropped and strengthening using CFRP wrap made it possible to not only recover the lost strength but also resulted in concrete strength greater than the original value.

• Journal of Korea Trade
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• 제26권2호
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• pp.65-83
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• 2022

Purpose - The purpose of this study is to evaluate the economic effects of FTAs using the concept of value-added exports. So far, the economic effects of FTAs have been dependent on decrease in import prices due to tariff cuts in importing countries, but the actual tariff reduction need to consider the value added of the exporting countries. Design/methodology - Value-added export refers to the added value created in the exporting country out of total exports. Among value-added exports, direct value-added export is interpreted as the Regional Value Contents (RVC), from which the economic effect of the FTA can be analyzed. A modified GTAP-VA model takes into account RVC in order to estimate accurate effects of FTAs. Findings - By the re-evaluation of the FTA based on the RVC, this paper makes it clear that the economic effects of the existing FTA methodology have the possibility of overestimation. In addition, as a new FTA with a strengthened Rules of Origin (ROO) is being initiated, a negative impact on international trade and GVC utilization may occur. Originality/value - This study introduces the concept of value-added export in analyzing the effects of FTAs. The new analysis methodology of this paper emphasizes the importance of value-added exports. Re-organization of GVCs would change regional trade agreements and empower ROO by weakening existing GVCs and transforming the value chain from global into regional scope.

• 대한토목학회논문집
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• 제35권1호
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• pp.39-48
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• 2015

섬유강화폴리머(FRP) 보강 철근콘크리트(RC) 구조물은 보강효과가 충분히 발휘되기 전에 보강재의 탈락으로 보강효과의 상실 및 구조부재의 갑작스러운 파괴를 야기할 수 있다. 현재 FRP 보강보의 박리파괴강도는 설계지침에서 제시된 보강재의 탈락변형률에 근거하여 무보강 RC보와 동일한 강도해석법을 적용하고 있다. 그러나, 각 설계지침에 따라 FRP 보강재의 탈락변형률이 달리 제시되고 있다. 따라서, 본 연구에서는 유리섬유강화폴리머(GFRP)로 보강된 RC보의 박리파괴 휨 강도 실험을 통해 각 설계기준에서 제시된 보강재 탈락변형률에 의한 박리파괴강도를 비교 평가하였다. 또한, 보강재 탈락에 의한 파괴는 콘크리트의 압축변형률이 극한변형률에 도달하기 전에 발생하므로, 본 연구에서는 재료의 비선형 응력분포를 고려한 해석을 수행하였다. 그리고, GFRP 보강 RC보의 설계 박리파괴강도 산정 시 강도설계법에 의해 산정된 무보강 RC보의 극한휨강도와 유사한 안전율을 나타낼 수 있는 강도식을 제시하였다.

• 대한예방한의학회지
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• 제6권2호
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• pp.48-63
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• 2002

The study aims to investigate the process of professional socialization of oriental medical students, to analyze influencing factors on it, and to compare the results with those of western medical students. Professional socialization, in the context of this study, means the process through which a layperson becomes a profession equipped with professional identity and values. A survey using specially designed questionnaire was carried out in 1999. The data were collected from 11 oriental medical colleges for 2,656 students. A total of 2,597 cases was finally included in the statistical analysis. Analysis of factors related to professional value found that oriental medical students thought highly of human-oriented factors, followed by science and status, and this trend remained unchanged as they moved on to qualification. Among professionalism related items, those involved in professional regulation and dominance factors showed high scores, while showing low scores on items related to bio-ethics and autonomy factors. Unlike items of professional value, those of professionalism showed a notable difference in attitude statistically by schooling level. The average scores of factors for professionalism increased with increasing schooling years. This trend proved that oriental medical students acquired professional norms and attitudes through their educational period. Multiple regression analysis with the factors related to professional value and professionalism as dependent variables found that independent variables had some impact on science, status, and clinical autonomy, but no impact on human, policy autonomy, and professional regulation factors. In conclusion, with increasing schooling years, professional norms and attitudes of oriental medical students were also strengthened. And, in spite of the differences in general propensity, they have a base consciousness in common with western medical students. The difference of mind-set and attitudes related to professionalism in the two groups, however, considering the necessity of future cooperative relations, indicated that a common curriculum between both schools is needed, and the education of social medicine should be strengthened in oriental medical colleges.

• 농촌지도와개발
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• 제3권2호
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• pp.273-284
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• 1996

This study aimed at measuring the rural people's level of value and morality, identifying its related variables, and drawing some implications for rural adult education. To measure their value and moral levels, 141 Yoncheon county adults were interviewed or asked to answer the questionnaires based on the Braithwaite and Law's(value) and Rest's(morality) instruments. The data were analyzed mainly by ANOVA, Chi square test and Pearson product-moment correlation. The major findings were: (1) The rural people mainly remained in vital feeling value(fourth) level out of five levels(religious holiness, spiritual, mind, vital feeling and sensible feeling value in order), (2) They remained in harmonious interpersonal expectations stage(fourth mortality level) out of six stage(universal ethical principles, social contract, social conscience maintenance, harmonious interpersonal expectation, instrumental purpose, and punishment/obedience in order), (3) Religion, the number of participation in adult education, and the length of such participation were three variables related to the level of value, and age, schooling years, and the number of family wane three variable related to their morality level, and (4) The relationship between value and morality levels was not significantly identified. Rural adult education needs to be more strengthened for improving their spiritual quality of life.

• Journal of information and communication convergence engineering
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• 제5권3호
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• pp.259-264
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• 2007

According to the development and wide use of broad band internet etc., diverse application technologies using large capacity data such as images have been progressed and in these systems, for accurate acquisition and precise applications of an original signal, the degradation phenomenon generated in the transmission process etc. should be removed. Noises have become known as the main cause of the degradation phenomenon and especially Gaussian noise represents characteristics occurring dependently in image signals and degrades detail information such as edge. In this paper, we removed Gaussian noise using a subdivided nonlinear function according to a threshold value and analyzed the histogram acquired from an edge image to establish a threshold value adaptively, and strengthened detail information of image by using the postprocessing. In simulation results, the proposed method represented excellent performance from comparison of MSE with existing methods.

• Earthquakes and Structures
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• 제5권6호
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• pp.703-731
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• 2013

In order to verify the applicability of buckling restrained braces (BRB's) and fiber reinforced polymer (FRP) sheets to the seismic strengthening of a low-rise RC building having the irregularities of a soft/weak story and torsion at the ground story, a series of earthquake simulation tests were conducted on a 1:5 scale RC building model before, and after, the strengthening, and these test results are compared and analyzed, to check the effectiveness of the strengthening. Based on the investigations, the following conclusions are made: (1) The BRB's revealed significant slips at the joint with the existing RC beam, up-lifts of columns from RC foundations and displacements due to the flexibility of foundations, and final failure due to the buckling and fracture of base joint angles. The lateral stiffness appeared to be, thereby, as low as one seventh of the intended value, which led to a large yield displacement and, therefore, the BRB's could not dissipate seismic input energy as desired within the range of anticipated displacements. (2) Although the strengthened model did not behave as desired, great enhancement in earthquake resistance was achieved through an approximate 50% increase in the lateral resistance of the wall, due to the axial constraint by the peripheral BRB frames. Finally, (3) whereas in the original model, base torsion was resisted by both the inner core walls and the peripheral frames, the strengthened model resisted most of the base torsion with the peripheral frames, after yielding of the inner core walls, and represented dual values of torsion stiffness, depending on the yielding of core walls.

• 콘크리트학회지
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• 제11권2호
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• pp.177-186
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• 1999

본 연구의 목적은 탄소섬유쉬트로 보강된 시험체의 주요 파괴모드인 계면모드인 계면박리 모드에 의한 부재의 파괴를 규명하는 것이다. 탄소섬유쉬트로 보강된 손상된 보시험체의 계면박리 모드를 해석하기 위하여 선형탄성 파괴역학(LEFM)의 컴플라이언스법과 유한요소법을 사용하여 계면파괴 역학변수인 에너지해방율(strain energy release rate, G)을 고찰하였다. 손상된 단순 보시험체의 해석결과, 최대 에너지해방율($G_{max}$)은 에폭시 접착두께에 관계없이 바깥 휨균열에서 시작된 계면 전단 균열 길이가 18mm 부근에서 발생하였다. 보강보의 강도 해석결과, 극한강도 설계법에 따른 단면의 공칭 휨 강도에 대한 계면박리에 의해 부재가 파괴되는 것으로 해석되었다. 또한 적용된 접착두께 1mm~3mm는 에너지해방율에 거의 영향을 미치지 않아 계면박리의 주요 인자가 아닌 것으로 나타났다.

• 한국융합학회논문지
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• 제10권11호
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• pp.125-130
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• 2019

사회전반에 걸쳐 드론의 활용도와 가치가 높아지고 있다. 그러나 국내 드론업체의 기술 부족, 드론관련 규제, 기술평가 항목 부재 등 정부의 지원과 투자가 부족한 것으로 나타났다. 따라서 본 연구는 대구지역 주민을 대상으로 드론산업 활성화를 위하여 강화시켜야 할 드론의 역량이 무엇인지 도출하기 위하여 통계분석을 실시하였다. 그 결과 드론의 수요만족도(가격, 품질, 서비스)는 드론의 역량강화 5개요인 중 물적, 사회적, 정책적 요인이 강화될 때 드론산업 활성화로 이어지는 것으로 나타났다. 결론적으로 우리나라 드론산업 활성화를 위해 강화시켜야 할 드론역량은 물적 요인(드론수요, 개발, 등록대수, 사업체 및 종사자 증가), 사회적 요인(국가차원의 홍보, 공교육기관 신설, 드론직업에 대한 올바른 이해와 인식), 및 정책적 요인(사생활 방지대책, 정부 재정지원, 법규와 제도 완화)이다. 이상의 3개 요인에 대하여 정부, 업계, 드론운용자가 삼위일체가 되어 개선 보완해 나아갈 때 우리나라 드론산업의 전망은 밝을 것으로 기대한다.

• 한국분말재료학회지
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• 제21권4호
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• pp.271-276
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• 2014

15Cr-1Mo base oxide dispersion strengthened (ODS) steel which is considered to be as a promising candidate for high- temperature components in nuclear fusion and fission systems because of its excellent high temperature strength, corrosion and radiation resistance was fabricated by using mechanical alloying, hot isostatic pressing and hot rolling. Torsion tests were performed at room temperature, leading to two different shear strain routes in the forward and reverse directions. In this study, microstructure evolution of the ODS steel during simple shearing was investigated. Fine grained microstructure and a cell structure of dislocation with low angle boundaries were characterized with shear strain in the shear deformed region by electron backscattered diffraction (EBSD). Grain refinement with shear strain resulted in an increase in hardness. After the forward-reverse torsion, the hardness value was measured to be higher than that of the forward torsion only with an identical shear strain amount, suggesting that new dislocation cell structures inside the grain were generated, thus resulting in a larger strengthening of the steel.