플라이애시 치환율 및 압축강도에 따른 콘크리트의 부착 거동

이형집(Lee, Hyung-Jib),서정인(Suh, Jeong-In),유성원(Yoo, Sung-Won) 한국건설순환자원학회 2016 한국건설순환자원학회 논문집 Vol.4 No.1

현재까지 하이볼륨 플라이애시 콘크리트의 연구는 슬럼프, 강도 및 내구성 등 기본적인 재 료성질에 대해서 주로 수행되어 왔다. 그러나 하이볼륨 플라이애시 콘크리트의 구조부재에의 적용을 위해서는 철근의 사용이 필수적이므로 그 부착특성에 대한 연구가 매우 중요하다고 할 수 있으나, 현재까지는 하이볼륨 플라이애시 콘크리트를 구조부재에 적용하기 위한 정확한 기준이나 콘크리트와 철근의 부착 특성에 관한 연구가 부족한 실정이다. 이 논문에서는 직접 인발 시험을 수행하여 하이볼륨 플라이애시 시멘트 콘크리트의 부착특성을 파악하고, 실험결과와 기존 연구결과를 비교하여 하이볼륨 플라이애시 시멘트 콘크리트의 부착특성을 평가하였다. 실험결과에 의하면, 하이볼륨 플라이애시 시멘트 콘크리트의 부착거동은 일반콘크리트와 유사하게 거동하는 것으로 나타났다. 또한 기존 연구결과와 비교하면, 하이볼륨 플라이애시 콘크리트의 부착강도는 묻힘길이가 클수록 부착강도를 과소평가하는 것으로 나타났다. Several researches on high volume fly ash concrete have been conducted to investigate its fundamental material properties such as slump, strength and durability and however, research on the structural behavior of bond strength is essential for the application of this high volume fly ash concrete to structural members because of the necessity of reinforcement. But the exact design code for application and researches on the bond behavior of high volume fly ash concrete lack yet. To achieve such a goal, this paper evaluates experimentally the bond behavior of high volume fly ash concretes by direct pull-out test and compares between the current test results and existing research results. By the test results, it is shown that the bond behavior of high volume fly ash concrete is similar to that of general concrete. And by the comparison between test and existing research, it is shown that bond stress of high volume fly ash concrete is underestimated, as the embedment length gets longer.

2면전단시험법에 의한 무근 HVFAC 콘크리트의 전단강도 평가

이형집(Hyung-Jib Lee),서정인(Jeong-In Suh),유성원(Sung-Won Yoo) 한국건설순환자원학회 2017 한국건설순환자원학회 논문집 Vol.5 No.3

본 연구에서는 플라이애시 첨가량과 콘크리트 압축강도를 실험변수로 설정하여 하이볼륨 플라이애시 시멘트를 사용한 무근콘크리트의 2면전단거동에 관한 실험을 수행한 후, 하이볼륨 플라이애시 시멘트 콘크리트의 전단특성을 파악하고자 하였다. 실험 결과, 전단 강도의 변화는 일반적으로 알려진 것과 유사하게 압축 강도의 증가에 따라 증가하는 경향이 나타났다. 콘크리트 구조설계기준(KCI, 2007)에서 제안한 콘크리트 전단강도 식은 실험결과와 유사한 경향을 보이고 있어 다량 치환된 플라이애시 시멘트 콘크리트의 전단강도는 콘크리트 구조설계기준에서 제시하고 있는 식을 준용하여도 큰 문제는 없을 것으로 예상된다. 한편 플라이애시 첨가율에 따른 다량 치환된 플라이애시 시멘트 콘크리트의 전단강도는 플라이애시 첨가율을 고려한 경우가 첨가율을 고려하지 않은 경우보다 훨씬 더 높은 상관성을 가지는 것으로 나타나, 비록 플라이애시 첨가율을 고려하지 않아도 현행 설계기준 식에 적절하기는 하지만 좀 더 상관성이 높은 식을 제안하였다. In this study, to determine the shear properties, experiments on the shear behavior of plain concrete with the high volume fly ash cement by double shear test were performed. Test parameters are fly ash content and concrete compressive strength. Experimental results show the tendency that the shear strength similarly increases with an increase in the compressive strength as is generally known. The concrete shear strength formula proposed in the concrete structural design code of KCI shows a similar tendency to the experimental results, and It is expected that the shear strength of the high volume fly ash cement concrete can be applied with the formula given in the concrete structural design code of KCI. When considering the fly ash content ratio, the shear strength of high volume fly ash cement concrete according to fly ash conctent ratio shows as having a far greater correlation than if it is not considered to fly ash content ratio. So, even though existing code can be appliable for non consideration of the fly ash content ratio, we proposed a formula that is much more relevant than that of concrete structural design code of KCI.

간헐폭기공정 반응조에서 혐기성상태 침전슬러지층으로의 초산주입에 의한 생물학적 인 제거효율의 향상

안규홍(Kyu Hong Ahn),이형집(Hyung Jib Lee) 한국수처리학회 1998 한국수처리학회지 Vol.6 No.3

Enhancing biological P-removal from wastewater with low COD:P ratio by intermittent injection of acetate into the anaerobically settled sludge layer during settling and decanting periods was studied in an intermittently-aerated cyclic activated sludge process. Injection of acetate induces phosphorus (P) release and uptake by phosphorus accumulating bacteria (PAB). The wastewater used in this experiment was actual domestic wastewater with average concentration of TCODcr = 129.7 ㎎/L, TN = 67.4 mg-N/L, and TP = 6.5 mg-P/L. Effective P-release inside the sludge layer was observed. The P-release capacity of PAB was strongly dependent on the nitrate concentration and the denitrification activity inside the sludge layer. It was concluded that acetate injection into the settled sludge layer can be used as very effective and stable method for inducing P-release, provided certain factors are properly controlled. Other benefits of acetate injection include: (1) better pH control (0.6 higher when acetate injected), (2) maintainenance of stable and high MLSS concentration (5.6 ㎎/L MLSS increase per ㎎/L acetate COD injected, at steady state), and (3) the increase of TN removal rate (0.06 ㎎-N/L additional TN removed per ㎎/L acetate COD injected at steady state).

하이 볼륨 플라이애쉬 철근콘크리트 보의 전단거동 실험

유성원(Sung-Won Yoo),이형집(Hyung-Jib Lee) 한국콘크리트학회 2014 콘크리트학회논문집 Vol.26 No.4

논문(論文) : 역삼투막 공정에서 화학적 세정에 의한 SiO2 scale 제거특성

독고석 ( Ko Seok Dock ),이형집 ( Hyung Jib Lee ) 대한상하수도학회 2010 상하수도학회지 Vol.24 No.1

하이 볼륨 플라이애쉬 철근콘크리트 보의 휨거동 실험

유성원(Sung-Won Yoo),이형집(Hyung-Jib Lee) 한국콘크리트학회 2014 콘크리트학회논문집 Vol.26 No.3

HBC media를 이용한 살수여상 공정에서 온도와 내부순환비의 영향 평가

이형집,독고석,양기해,정팔진 대한상하수도학회 2003 상하수도학회지 Vol.17 No.6

Trickling filters have been used in the biological treatment of municipal and industrial wastewater for many years. They are nonsubmerged fixed-film biological reactors using rock or plastic packing media over which wastewater is distributed continuously. Recently new packing medium with high specific surface area and low specific gravity has been developed instead of gravel. In this study the trickling filter system using polyethylene HBC media was applied for treating wastewater from a restaurant. The water quality of treated water according to the variations of recycling ratio, DO, OCD, and temperature were monitored in the period of 90 days. Based on the results from this study, it can be concluded that the higher treatment efficiency is obtained from the condition of low recycling ratio (around N = 1∼10), Hardly has the recycling ratio an influence on the efficiency at low surface loading, while it is vice versa at high surface loading. Trickling filter system has no merit when the temperature goes down under 5℃ compared with the conventional activated sludge system.

꽃게(Bule Crab)가공 식품 제조 공정상 발생된 폐수 및 폐기물의 혐기성 생분해 가능성(1)

이형집 대한상하수도학회 1997 상하수도학회지 Vol.11 No.4

Disposal of blue crab wasted represents a significant problem to processors, who are limited with respect to acceptable disposal alternatives. Anaerobic bioconversion technology was investigated to determine an environmentally sound and economic disposal method for these wastes. In the study ultimate methane yield for total crab solid waste was 0.180 m^3/kg VS added and biodegradation rate constant was 0.15 day^-1. Methane yield of the bench-scale reactor operated on similar feedstock was 0.189 m^3/kg VS added and biodegradation rate constant was 0.06 day^-1. These results indicate that anaerobic bioconversion of blue crab wastes was technically feasible. Use of anaerobic bioconversion technology can be an attractive option for blue crab processing waste management. The by-product methane gas could he used for maintain a number of processing operations (i.e, heat for cooking, or keeping temperature of digester constant).

꽃게(Blue Crab)가공 식품 제조 공정상 발생된 폐수 및 폐기물의 혐기성 생분해 가능성(2) : 공정상 발생된 폐기물의 혐기성 생분해 가능성 증대를 위한 효소적 전처리 Enzymatic Pretreatment for Improving the Anaerobic Bioconversion Potential of Blue Crab Processing Wastes

이형집 대한상하수도학회 1998 상하수도학회지 Vol.12 No.2

In use of anaerobic bioconversion shellfish wastes present special problems, since the chitinous structures in the shell fraction degrade very slowly in an anaerobic environment. Enzymatic pretreatment method was evaluated for improving the anaerobic bioconversion potential of blue crab processing wastes. An enzymatic pretreatment using chitinase enhanced the ultimate methane yield and biodegradation rate constant for total crab solid wastes by 15% and 19% respectively, above those of the untreated wastes. When the enzymatic pretreatment applied to the shell fraction alone, it resulted in increase of 34% in the ultimate methane yield and 38% in the reaction rate. The results indicate that anaerobic bioconversion of these wastes is technically feasible and enzymatic pretreatment will improve the efficiency of the process.

용존공기부상법(DAF)에서 충돌메커니즘의 영향요인 분석

독고석,이형집 대한상하수도학회 2002 상하수도학회지 Vol.16 No.5

In this research, the theoretical modeling of DAF which was obtained by trajectory analysis has been verified. Especially, the effects of electrostatic nature and particle size of bubble and particle (floc) was focused. To measure the electrostatic nature of bubble, zeta potential measuring setup was made in a well controlled laboratory. The effects of several operational parameters in DAF process are investigated on a system composed of batch DAF reactor, microscope and video system. The effect of pH on the removal efficiency of DAF is presented. The effect of mixing time is presented. The effect of zeta potential of floc and bubbles with the addition of coagulant is presented. It is found that all the phenomena can be explained primarily from the electrostatic nature of bubble and particle and secondarily from the effect of particle size. The findings from this research are compared and verified with the results of DAF modeling by α_bp. This research will be helpful to understand and explain the process better and possibly can be used to modify and improve the DAF process.