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성숙도 방법을 이용한 불포화 폴리에스터 수지 폴리머 콘크리트의 압축강도 예측
최기봉,김남길,이윤수,연규석,Choi, Ki-Bong,Jin, Nan Ji,Lee, Youn-Su,Yeon, Kyu-Seok 한국농공학회 2017 한국농공학회논문집 Vol.59 No.6
This study investigated to predict the compressive strength of unsaturated polyester resin based polymer concrete using the maturity method. The test results show that the development of the compressive strength increased exponentially until an age of 24 hours. After 24 hours, the development of the compressive strength just increased gradually. This test result shows that the strength of unsaturated polyester resin based polymer concrete was developed mainly at the early age. Estimated datum temperature of unsaturated polyester resin based polymer concrete was $-20.67^{\circ}C$ which was much lower than of datum temperature ($-10^{\circ}C$) of Portland cement concrete. Also, this study result shows that the existing maturity index associated with Portland cement concrete was not applicable for polymer concrete because curing time of Portland cement concrete is different clearly with curing time of polymer concrete. The cause of different curing time was that there were different curing mechanisms between Portland cement concrete and polymer concrete. In order to best apply the experimental data to a model, CurveExpert Professional, the commercial software, was used to determine the predictive model regarding the compressive strength of unsaturated polyester resin based polymer concrete. As a result, Gompertz Relation or Weibull Model was an appropriate model as a predictive model. The proposed model can be used to predict the compressive strength, especially, it is more useful when the maturity is in the range between $40^{\circ}C{\cdot}h^{0.4}$ and $900^{\circ}C{\cdot}h^{0.4}$.
최기봉,윤희주,차승희,최정도 ( Ki Bong Choi,Hee Ju Youn,Seung Hee Cha,Jung Do Choi ) 한국센서학회 1997 센서학회지 Vol.6 No.5
Fiber-optic evanescent wave sensor was designed and fabricated to detect mouse immunoglobulin G(IgG) with decladed optical fiber on which anti-mouse IgG was immobilized. A sensitivity obtained by any direct or competitive method was lower than 1 ㎍/㎖. Anti-mouse IgG was immobilized on 93.9% of core surface of optical fiber by simple adsoption method. The effect of postcoating using bovine serum albumin to remove non-specific binding was not observed. As the ratio of fluorescein to mouse IgG increased, the fluorescence signal increased, but that increase showed no linear relationship. Our fiber--optic sensor system could be used as immunosensor by measuring evanescent fluorescence in antigen-antibody reaction with good sensitivity below lug/mP level.
바잘트섬유 시트로 전단보강한 철근콘크리트 보의 전단경간비에 따른 거동특성
최기봉 ( Choi Ki-bong ) 한국복합신소재구조학회 2021 복합신소재구조학회논문집 Vol.12 No.6
이 연구는 바잘트 섬유시트로 전단보강한 철근콘크리트 보의 전단경간비에 따른 구조물의 구조적 거동을 실험을 통해 확인하였다. 철근콘크리트 보의 전단보강은 무보강, 45도, 90도, U형보강을 변수로 두었으며 전단경간비에 따른 실험결과 U형으로 보강하였을 때 철근콘크리트 보의 전단보강효과가 높음을 확인하였다. In this study, the structural behavior of reinforced concrete beams shear-strengthened with basalt fiber sheets based on the shear span ratio was investigated via experiments. The experimental parameters for the shear strengthening of reinforced concrete beams comprised beams without reinforcement and 45°, 90°, and U-shaped reinforcements. Experimental results showed that the shear strengthening effPect of the reinforced concrete beams was excellent when the basalt fiber sheet was subjected to U-shape reinforcement.
최기봉 ( Ki Bong Choi ),이동곤 ( Dong Gon Lee ),노현구 ( Hyun Gu Roh ),이창식 ( Chang Sik Lee ) 한국액체미립화학회 2014 한국액체미립화학회 학술강연회 논문집 Vol.2014 No.-
The aim of this work is to investigate the effect of ambient conditions in the constant volume spray chamber on the mixture formation of diesel-ethanol blended fuels. In order to analyze the air and fuel mixture formation, spray behaviors were obtained from the visualization system, and the effects of ethanol blending fuels on the spray characteristics were compared to that of neat diesel fuel. In addition, the spray characteristics such as spray tip penetration, spray cone angle, and spray area of ethanol blended fuel were analyzed by using the visualization images obtained from visualization system. In order to visualize diesel-ethanol sprays, a visualization system composed of a blending fuel supply system, a high-speed CCD camera, a high-pressure spray chamber, and an image data acquisition system. This experimental results showed that the spray penetration of diesel and ethanol blended fuel was slightly longer than that of a neat diesel fuel. The spray cone angle of ethanol blends showed wider angle than that of diesel fuel by increased amount of the ethanol blending ratio. The spray tip penetration of diesel-ethanol blends decreased with the increase of fuel injection pressure, and spray cone angle increased in accordance with the increase of ambient pressure. In this work, the effect of ambient pressure on the spray macroscopic characteristics was conducted under the various ethanol blending ratios.
최기봉 ( Choi¸ Ki Bong ),김강호 ( Kim¸ Kang Ho ),곽승택 ( Kwak¸ Seung Taek ) 한국구조물진단유지관리공학회 2000 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.4 No.2
An integrated experimental-theoretical investigation was performed on the dowel behavior at high-strength reinforced concrete in the high-rise building. Results of an experimental study on the dowel action of beam longitudinal bars at beam-column interfaces in high-strength concrete(450 ~ 600kgf/cm<sup>2</sup>) frames are presented. The crack patterns and dowel load-deflection diagrams are presented for specimens with different sizes of dowel bars. Test results indicate that the stiffness and energy dissipation capacity of dowel bars deteriorate severely with repetition of inelastic load cycles.
7,8-Dioxo-A-norerythrinan-6-carboxylates의 합성
최기봉(Ki Bong Choi),하연철(Yeun Chul Ha),황기운(Ki Woon Hwang),서병일(Byung Il Seo),한병곤(Byung Kon Han),서원준(Won Jun Seo) 대한약학회 1995 약학회지 Vol.39 No.4
7,8-Dioxo-A-norerythrinan-6-carboxylates (1-2) were synthesized by acid catalyzed cyclization of 2,3-dioxo-1-phenethyl-octahydrocyclopenta[b]pyrrole-3a-7carboxylates (3-6). The preparative condition and characteristic of rigid A-norerythrinan skeleton (E) were discussed with brief interpretation.