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IR spectrometer 를 이용한 부유 입자의 IR 차폐능 측정
최기봉,고은미,안경일 ( Ki Bong Choi,Eun Mee Goh,Kyung Il Ahn ) 한국화학공학회 1995 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.33 No.4
To examine the correlationship between IR attenuation and physical properties of suspended particles, IR spectrometer can be used effectively. Several graphite flakes and metallic powders were suspended in a liquid cell and the IR attenuations were measured. The results were analyzed in terms of their physical properties such as shape, purity and mean particle size. It was found out that the powder which had smaller mean size, higher purity and more developed flake type showed higher IR attenuation. JG02 and BR06 showed the highest mass and volume extinction coefficient, α=1.41 ㎡/g, β=2.7 ㎡/㎤, respectively. This technique was considered as more efficient method than the conventional one using aerosol chamber. It could reduce the error caused by external factors and was even more simple to measure the physical effects of various kinds of suspended powders.
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.
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 ( 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.
다방향성 바잘트 섬유 시트로 전단보강한 철근콘크리트 보의 전단성능
최기봉 ( Choi Ki-bong ) 한국복합신소재구조학회 2022 복합신소재구조학회논문집 Vol.13 No.5
이 연구는 다방향성 바잘트 섬유 시트로 보강한 철근콘크리트 보의 보강방법에 따른 전단거동을 실험을 통해 확인하였다. 실험변수는 보강방법(무보강, 45도 90도 U형)과 보강겹수(0, 1 2겹)를 변수로 두었으며 전단강도실험결과 바잘트섬유시트를 90도로 1겹 보강하였을 때 최대 11% 이상의 보강성능을 확인하였다. 또한, 유효변형률을 검토한 결과 섬유양이 증가함에 따라 유효변형률이 감소함을 확인하였다. The shear behavior according to the reinforcement method of concrete beams reinforced with multidirectional basalt fiber sheets was verified through experiments. The experimental parameters were the reinforcement method (non-reinforcement, 45°, 90°, and U-shaped) and the number of reinforcement layers (0, 1, and 2 layers). The shear strength test revealed an up to 11% increase in shear performance when a basalt fiber sheet was used as reinforcement in a single layer at 90°. Additionally, the effective strain decreased as the amount of FRP was increased.
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.