전기로 산화 슬래그 잔골재를 사용한 콘크리트의 팝아웃현상 및 보수공법 제안

이건철,이문,이세현,Lee, Gun-Cheol,Lee, Mun-Hwan,Lee, Sea-Hyun 한국건설순환자원학회 2007 한국건설순환자원학회지 Vol.3 No.1

Since pop-outs are occurred recently on concrete surface occasionally, it is needed to find out accurate causes and to suggest appropriate methods. On this study, it is investigated the occurrence mechanism of pop-outs caused by electric arc furnace Oxidizing slags as fine aggregate for concrete. As a result, it is investigated the cause of pop-outs that extremely small quantities of free CaO and free MgO in the electric furnace slag react with water to produce $Ca(OH)_2$ and $Mg(OH)_2$, so that their volumes are expanded and erupted about two times. As a resolution, it is needed to remove the potential cause of expansion by replacing the deteriorated concrete section up to the depth to secure the safe of structural element with repairing polymer mortar, especially more than 50MPa.

일본의 석탄가스화 슬래그 골재의 규격 제정 현황

이건철,한천구,김찬영,Lee, Gun-Cheol,Han, Cheon-Goo,Kim, Chan-Young 한국건설순환자원학회 2021 한국건설순환자원학회지 Vol.16 No.3

건설폐기물을 콘크리트용 순환골재로 활용하기 위한 과제와 전망

이건철,Lee, Gun-Cheol 한국건설순환자원학회 2015 한국건설순환자원학회지 Vol.10 No.3

세계유산$\cdot$국보건축물의 진단사례

이건철,Lee, Gun-Cheol 한국구조물진단학회 2006 한국구조물진단유지관리공학회지 Vol.10 No.1

잔골재 대체재로서 석탄회를 이용한 초속경 보수모르타르의 기초적 특성에 관한 연구

이건철,오동욱,김영근,조정기,Lee, Gun-Cheol,Oh, Dong-Uk,Kim, Young-Geun,Cho, Chung-Ki 한국건설순환자원학회 2011 한국건설순환자원학회지 Vol.6 No.1

본 연구에서는 산업부산물로서 재활용율이 낮은 바텀애쉬와 혼화재를 이용하는 에코개념의 터널 보수용 초속경 그라우트 모르타르 개발을 목적으로 실시공 환경조건의 온도하에서 초속경 그라우트 모르타르의 기초적 특성에 대하여 검토하였다. 실험결과, 유동성 및 응결시간은 B > C > A type 순으로 크게 나타났으며, 온도조건별로는 상온보다 저온에서 더 지연되었다. 압축강도, 휨강도, 부착강도는 3 type 모두 비슷하게 나타났는데, 압축강도는 저온조건에서는 초기에 강도가 작았지만 장기재령에서는 상온조건과 유사한 강도가 나타났고, 휨강도는 초기에는 강도가 유사했지만 장기재령에서는 상온조건이 크게 나타났으며, 부착강도는 상온조건보다 저온조건이 평균 35 % 저하되었다. 길이변화는 A > C > B 순으로 저온조건이 상온조건보다 2배로 나타났으며 고로슬래그 미분말을 취환한 경우 현저히 감소되었다. 물흡수 계수 및 습기투과 저항성은 C > A > B 순으로 크게 나타났고 바텀애쉬를 치환할 경우 다공질의 영향으로 크게 증가되었다. In this study, in order to develop ultra rapid hardening mortar(URHM) for tunnel repairs using bottom ash of low recycle ratio and Admixture as Eco concept, fundamental properties of URHM on temperature condition of construction field were performed. Test result, URHM of three types for fluidity and setting time were as in the following : B > C > A. Those for low temperatures were later than the standard condition. Compressive, bending and bond strength were similar with three types as follow. In compressive strength, initial strength of the low were smaller than the standard but the low in the long-term were similar with the standard. On the contrary to this, bending strength were similar in initial strength but the low in the long-term were smaller than the standard. The low in bond strength was average 35% less than the standard. Length changes was as in the following : A > C > B. the low is two times much as the standard but the case using blast furnace slag particles noticeably reduced length changes. Water absorption coefficient and water vapor resistance were as in the following : C > A > B. In case of URHM added bottom ash, water absorption coefficient and water vapor resistance were increased because bottom ash is porous material.

재생골재콘크리트 M의 JIS(Japan Industrial Standard) 제정

이건철,Lee, Gun Cheol 한국건설순환자원학회 2007 한국건설순환자원학회지 Vol.3 No.1

잔골재 대체재로서 바텀애쉬를 이용한 초속경 그라우트재의 수밀성 및 내구특성

이건철,오동욱,조병영,김영근,조정기,Lee, Gun-Cheol,Oh, Dong-Uk,Cho, Byoung-Young,Kim, Young-Geun,Cho, Chung-Ki 한국건설순환자원학회 2011 한국건설순환자원학회지 Vol.6 No.3

본 연구에서는 산업부산물로서 재활용율이 낮은 바텀애쉬와 혼화재를 이용하는 에코개념의 터널 보수용 초속경 그라우트 모르타르 개발을 목적으로 실시공 환경조건의 온도하에서 초속경 그라우트 모르타르의 수밀성 및 내구특성에 대하여 검토하였다. 수밀성으로 투수량 및 물흡수계수는 석탄회를 이용하는 시리즈 II의 경우가 증가하는 것으로 나타났으며, 온도조건별로는 $20^{\circ}C$ 양생조건이 $5^{\circ}C$ 양생조건 보다 투수량이 적은 것으로 나타났다. 또한, 본 연구범위 모든 시료는 KS F 4042(콘크리트 구조물 보수용 폴리머 시멘트 모르타르) 투수량 기준인 20g 이내를 만족하는 것으로 나타났다. 내구성으로 중성화 저항성은 고로슬래그 미분말로 치환 사용에 따른 단위시멘트량 감소로 약간 저하하는 것으로 나타났다. 또한, 내알칼리성 및 내산성 결과는 시리즈 I의 경우 수산화칼슘용액에 침지후의 압축강도가 침지전의 압축강도에 비해 저하하는 것으로 나타났다. 반면, 시리즈 II의 경우 강도저하가 미비한 것으로 나타났으며, $5^{\circ}C$ 양생조건의 경우 C 타입의 시멘트를 제외하고는 28일 재령의 압축강도와 동등한 값을 나타내어 고로슬래그 미분말 및 버텀애쉬를 치환 사용한 경우 내알칼리성 및 내산성이 큰 것 알 수 있었다. In this study, in order to develop ultra rapid hardening mortar(URHM) for tunnel repairs using bottom ash of low recycle ratio and Admixture as Eco concept, watertightness and durability properties of URHM on temperature condition of construction field were performed. Test result, seepage quantity and water absorption coefficient regarding watertightness of URHM were as in the following : series II > series I. Seepage quantity for the standard condition were smaller than low temperatures. all specimens were satisfied below 20g as standards of seepage quantity on KS F 4042. Because of the decrease of unit cement content by to replacement of blast furnace slag, the neutrlization resistance for durability properties was reduced. The result of alkali resistance and acide resistance, compressive strengths for specimens soaked in calcium hydroxide solution of seriesI were lower than compressive strengths for specimens not soaked. On the other hand, the case of series II show that the deterioration of compressive strengths for specimens was not almost showed. Compressive strengths of specimens soaked were similar with specimens not soaked except series II-C in $5^{\circ}C$. Therefore, specimens using both blast furnace slag and bottom ash were good in alkali resistance and acide resistance.

구두 굽 높이의 차이가 균형 수행능력에 미치는 영향

이건철,정혜미,김상범,곽현,Lee Geon-Cheol,Jeong Hye-MI,Kim Sang-Beom,Kwak Hyun 대한물리치료학회 2004 대한물리치료학회지 Vol.16 No.3

Purpose : The purpose of this study is to research the effects of the differences in shoe heel height on balanced performances with a balance master. Method : 40 healthy female adults were divided into 2 groups at random. All the female participants were tested by a balance master system. Differences were analyzed according to high heel shoes and low heel shoes. The ability of static postural balance control was measured by modified CTSIB and unilateral stance test, while that of dynamic postural balance control was measured by LOS (limit of stability) and rhythmic weight shift, among the programs of a balance master. Result : 1. There is no significant correlation between the ability of static and dynamic postural balance control before main test without the shoes. 2. Movement velocity and directional control ability were significant correlation compared result of in high heel shoes and low heel shoes group. Conclusion : In conclusion, the test results of the high heeled shoe group and the low heeled shoe group through a balance master system showed that the former one is inferior to the latter one.

시지각적 되먹임 훈련이 뇌졸중 환자의 동적자세 균형에 미치는 영향

이건철,윤정규,Lee, Geon-Cheol,Yoon, Jung-Gyu 대한물리치료과학회 2002 대한물리치료과학회지 Vol.9 No.2

This study is aimed to compare the effect of visuo-perceptual biofeedback sitting balance training and conventional sitting balance training using Balance Master on stroke patients with that of program in order to analyze the effect it has on dynamic postural balance. The subjects are twenty-four stroke patients who are receiving physical therapy in Ilsan Paik Hospital and can maintain sitting posture by themselves. These patients were divided to control group and experimental group randomly. In order to compare to control and experimental group before and after the balance training, they were tested with Mann-Whitney U test and in order to compared the changes before and after the balance training, they were tested with Wilcoxon signed-ranks test. The results are as follows: we measured the ability of dynamic posture balance control with limit of stability(LOS) test and rhythmic weight shift test. There was an increasing improvement in the ability of dynamic posture balance control of the experimental group that had visuo-perceptual biofeedback sitting balance control training using the Balance Master(p<0.05, p<0.01). According to the results from above, compared to conventional sitting balance training programs, visuo-perceptual biofeedback sitting balance control training using the Balance Master is considered to be a more valuable therapy in balance control improvement and physical function improvement. It is considered that if the weak points are made up, the training with Balance Master will give help to stroke patients and to patients with balance control disabilities and will further more contribute to successful rehabilitation therapy.

고강도 콘크리트용 시멘트계 메트릭스의 레올로지 성질 및 합리적 유동성 평가에 관한 연구

이건철,조병영,오동욱,Lee, Gun-Cheol,Cho, Byoung-Young,Oh, Dong-Uk 대한건축학회 2012 대한건축학회논문집 Vol.28 No.1

In this study, both rheological aspect for fluidity and correlation for fluidity evaluation methods of cement paste and mortar for high strength concrete mix are considered. Effects of the fiber and correlation of fluidity evaluation methods for cement paste and mortar of each mix in four high strength concrete mix of 40~100 MPa used on the site are reviewed. As a result, cementitious matrix appeared high fluidity, but fluidity in case of adding fiber into plain mix has been decreased because of high viscosity and networking effect of fiber. In addition, the relation of between each fluidity evaluation method and rheological parameters has rather lower interrelationship in case of slump flow, but it showed higher interrelationship with between both 500mm arrival time of L flow test and funneling time and rheology integer. Therefore, in case of high fluidity concrete such as high strength concrete, The physical evaluation including shear-strain rate in addition to fluidity evaluation such as flow is important.